please visit my new homepage (under contruction)...
http://site.google.com/site/pawanbabel
suggestions are welcome.
Sunday, September 20, 2009
Thursday, August 6, 2009
About IIT 2009
Procedure for Preparing Merit Lists
Only those candidates who attempted both Paper 1 and Paper 2 were considered for preparing the merit lists. The marks obtained by a candidate in Chemistry, Mathematics and Physics are considered to be the sum of the marks obtained in the corresponding parts in Paper 1 and Paper 2. The sum of the marks obtained in the individual subjects in JEE will be the aggregate mark for the candidate.
Minimum Qualifying Mark for Ranking (MQMR)
The average of the marks scored by all such candidates was computed for each of the three subjects. These averages were 10.44, 10.12 and 7.81 (up to two decimals) for Chemistry, Mathematics and Physics, respectively. These are the minimum qualifying mark for ranking (MQMR) in the individual subjects. Thus, a candidate qualified for ranking without relaxed norms only when he/she scored at least 11, 11 and 8 marks in Chemistry, Mathematics and Physics, respectively.
Tie-Break
The tie-break criterion in the merit lists adopted for awarding ranks to the candidates who have scored the same aggregate marks is as follows. For each subject, the mean (i.e., the average) marks has been calculated on the basis of the marks obtained by those candidates who have scored more than or equal to MQMR in that subject. These averages are 37.68, 35.29 and 33.68 (up to two decimals) for Chemistry, Mathematics and Physics, respectively. Thus, the average is the lowest for Physics and highest for Chemistry. Among the candidates having the same aggregate marks, a candidate has been ranked higher than the rest, if he/she has scored higher marks in Physics. If there is a tie after this, then a candidate has been ranked higher than the rest, if he/she has scored higher marks in Physics. Candidates tied even after this procedure, have been given the same rank.
Common Merit List (CML)
Based on the MQMR in the individual subjects, the aggregate marks obtained by the candidates and the above tie-breaking procedure and, a common merit list (CML) was prepared, without any relaxed criteria. The CML contained 8295 candidates in all. The aggregate marks scored by the last candidate in the CML is 178 and this is the CML cut-off score (CCS).
Category Merit Lists
Next, the merit list for OBC candidates has been prepared with 10% relaxation in MQMR and CML cut-off score. Similarly, merit lists for SC, ST and PD candidates have been prepared with 50% relaxation in MQMR and CML cut-off score. The numbers of candidates appeared in OBC, SC, ST and PD merit lists are 1930, 967, 208 and 138, respectively.
Preparatory Merit Lists
To select candidates for Preparatory Course against the unfilled seats reserved for SC, ST and PD candidates, three Preparatory Merit Lists have been prepared with relaxation of 50% in MQMR and aggregate cut-off for SC, ST and PD merit lists. The number of candidates in the preparatory merit lists was at most 1.5 times the number of vacant seats in these categories.
Extended Merit Lists
Extended merit lists for GE (common), OBC, SC, ST and PD candidates were prepared with further relaxations in aggregate cut-off, but not in MQMR, for use of other institutes like IISERs, IIST, RGIPT and IIMS. The lengths of these lists are six times the lengths of corresponding main merit lists of JEE-2009.
Minimum Qualifying Mark for Ranking (MQMR) and Aggregate Cut-off
Merit List
MQMR
Aggregate Cut-off
(out of 480)
Chemistry (out of 160)
Mathematics
(out of 160)
Physics
(out of 160)
General (CML)
11
11
8
178
OBC
10
10
8
161
SC
6
6
4
89
ST
6
6
4
89
PD
6
6
4
89
Marks of the first and the last ranked candidates in JEE merit lists
Merit List
Marks of the first candidate
Marks of the last candidate
Chemistry
Mathematics
Physics
Aggregate
Chemistry
Mathematics
Physics
Aggregate
General (CML)
122
153
149
424
72
31
75
178
OBC
126
143
144
413
66
63
32
161
SC
115
100
111
326
43
41
5
89
ST
106
118
95
319
25
40
24
89
PD
115
87
87
289
20
36
33
89
Maximum and minimum marks scored in different subjects by candidates in JEE merit lists
Merit List
Chemistry
Mathematics
Physics
Maximum
Minimum
Maximum
Minimum
Maximum
Minimum
General (CML)
132
11
156
12
156
15
OBC
131
14
145
14
149
15
SC
115
7
119
6
124
4
ST
106
8
118
6
103
4
PD
115
11
115
6
110
6
Aggregate cut-off for Extended Merit Lists
Merit list
General
OBC
SC
ST
PD
Aggregate cut-off
56
62
17
16
17
Aggregate Total of Different Categories (500th for GE and 100th for OBC/SC/ST/PD)
Common Merit List
Rank
Aggregate Marks
1
424
501
302
1001
278
1501
262
2001
249
2501
239
3001
230
3501
223
4001
216
4501
211
5001
205
5501
200
6001
196
6501
191
7001
187
7501
184
8001
180
8295
178
OBC Category
Rank
Aggregate Marks
1
413
101
282
201
260
301
244
401
231
501
223
601
216
701
210
801
204
901
199
1001
194
1101
190
1201
186
1301
181
1401
177
1501
174
1601
171
1701
167
1801
164
1901
161
1930
161
SC Category
Rank
Aggregate Marks
1
326
101
170
201
146
301
132
401
121
501
112
601
105
701
99
801
95
901
91
967
89
ST Category
Rank
Aggregate Marks
1
319
101
114
201
91
208
89
PD Category
Rank
Aggregate Marks
1
289
101
108
138
89
Aggregate Total and subject-wise marks for the first and last admitted candidates
Common Merit List
Maths
Physics
Chemistry
Total
AIR
153
149
122
424
1
31
75
72
178
8295
OBC Category
Maths
Physics
Chemistry
Total
AIR
143
144
126
413
1
63
32
66
161
1930
SC Category
Maths
Physics
Chemistry
Total
AIR
100
111
115
326
1
41
5
43
89
967
ST Category
Maths
Physics
Chemistry
Total
AIR
118
95
106
319
1
40
24
25
89
208
PD Category
Maths
Physics
Chemistry
Total
AIR
87
87
115
289
1
36
33
20
89
138
Only those candidates who attempted both Paper 1 and Paper 2 were considered for preparing the merit lists. The marks obtained by a candidate in Chemistry, Mathematics and Physics are considered to be the sum of the marks obtained in the corresponding parts in Paper 1 and Paper 2. The sum of the marks obtained in the individual subjects in JEE will be the aggregate mark for the candidate.
Minimum Qualifying Mark for Ranking (MQMR)
The average of the marks scored by all such candidates was computed for each of the three subjects. These averages were 10.44, 10.12 and 7.81 (up to two decimals) for Chemistry, Mathematics and Physics, respectively. These are the minimum qualifying mark for ranking (MQMR) in the individual subjects. Thus, a candidate qualified for ranking without relaxed norms only when he/she scored at least 11, 11 and 8 marks in Chemistry, Mathematics and Physics, respectively.
Tie-Break
The tie-break criterion in the merit lists adopted for awarding ranks to the candidates who have scored the same aggregate marks is as follows. For each subject, the mean (i.e., the average) marks has been calculated on the basis of the marks obtained by those candidates who have scored more than or equal to MQMR in that subject. These averages are 37.68, 35.29 and 33.68 (up to two decimals) for Chemistry, Mathematics and Physics, respectively. Thus, the average is the lowest for Physics and highest for Chemistry. Among the candidates having the same aggregate marks, a candidate has been ranked higher than the rest, if he/she has scored higher marks in Physics. If there is a tie after this, then a candidate has been ranked higher than the rest, if he/she has scored higher marks in Physics. Candidates tied even after this procedure, have been given the same rank.
Common Merit List (CML)
Based on the MQMR in the individual subjects, the aggregate marks obtained by the candidates and the above tie-breaking procedure and, a common merit list (CML) was prepared, without any relaxed criteria. The CML contained 8295 candidates in all. The aggregate marks scored by the last candidate in the CML is 178 and this is the CML cut-off score (CCS).
Category Merit Lists
Next, the merit list for OBC candidates has been prepared with 10% relaxation in MQMR and CML cut-off score. Similarly, merit lists for SC, ST and PD candidates have been prepared with 50% relaxation in MQMR and CML cut-off score. The numbers of candidates appeared in OBC, SC, ST and PD merit lists are 1930, 967, 208 and 138, respectively.
Preparatory Merit Lists
To select candidates for Preparatory Course against the unfilled seats reserved for SC, ST and PD candidates, three Preparatory Merit Lists have been prepared with relaxation of 50% in MQMR and aggregate cut-off for SC, ST and PD merit lists. The number of candidates in the preparatory merit lists was at most 1.5 times the number of vacant seats in these categories.
Extended Merit Lists
Extended merit lists for GE (common), OBC, SC, ST and PD candidates were prepared with further relaxations in aggregate cut-off, but not in MQMR, for use of other institutes like IISERs, IIST, RGIPT and IIMS. The lengths of these lists are six times the lengths of corresponding main merit lists of JEE-2009.
Minimum Qualifying Mark for Ranking (MQMR) and Aggregate Cut-off
Merit List
MQMR
Aggregate Cut-off
(out of 480)
Chemistry (out of 160)
Mathematics
(out of 160)
Physics
(out of 160)
General (CML)
11
11
8
178
OBC
10
10
8
161
SC
6
6
4
89
ST
6
6
4
89
PD
6
6
4
89
Marks of the first and the last ranked candidates in JEE merit lists
Merit List
Marks of the first candidate
Marks of the last candidate
Chemistry
Mathematics
Physics
Aggregate
Chemistry
Mathematics
Physics
Aggregate
General (CML)
122
153
149
424
72
31
75
178
OBC
126
143
144
413
66
63
32
161
SC
115
100
111
326
43
41
5
89
ST
106
118
95
319
25
40
24
89
PD
115
87
87
289
20
36
33
89
Maximum and minimum marks scored in different subjects by candidates in JEE merit lists
Merit List
Chemistry
Mathematics
Physics
Maximum
Minimum
Maximum
Minimum
Maximum
Minimum
General (CML)
132
11
156
12
156
15
OBC
131
14
145
14
149
15
SC
115
7
119
6
124
4
ST
106
8
118
6
103
4
PD
115
11
115
6
110
6
Aggregate cut-off for Extended Merit Lists
Merit list
General
OBC
SC
ST
PD
Aggregate cut-off
56
62
17
16
17
Aggregate Total of Different Categories (500th for GE and 100th for OBC/SC/ST/PD)
Common Merit List
Rank
Aggregate Marks
1
424
501
302
1001
278
1501
262
2001
249
2501
239
3001
230
3501
223
4001
216
4501
211
5001
205
5501
200
6001
196
6501
191
7001
187
7501
184
8001
180
8295
178
OBC Category
Rank
Aggregate Marks
1
413
101
282
201
260
301
244
401
231
501
223
601
216
701
210
801
204
901
199
1001
194
1101
190
1201
186
1301
181
1401
177
1501
174
1601
171
1701
167
1801
164
1901
161
1930
161
SC Category
Rank
Aggregate Marks
1
326
101
170
201
146
301
132
401
121
501
112
601
105
701
99
801
95
901
91
967
89
ST Category
Rank
Aggregate Marks
1
319
101
114
201
91
208
89
PD Category
Rank
Aggregate Marks
1
289
101
108
138
89
Aggregate Total and subject-wise marks for the first and last admitted candidates
Common Merit List
Maths
Physics
Chemistry
Total
AIR
153
149
122
424
1
31
75
72
178
8295
OBC Category
Maths
Physics
Chemistry
Total
AIR
143
144
126
413
1
63
32
66
161
1930
SC Category
Maths
Physics
Chemistry
Total
AIR
100
111
115
326
1
41
5
43
89
967
ST Category
Maths
Physics
Chemistry
Total
AIR
118
95
106
319
1
40
24
25
89
208
PD Category
Maths
Physics
Chemistry
Total
AIR
87
87
115
289
1
36
33
20
89
138
Sunday, June 7, 2009
SYLLABUS FOR TEST PAPERS OF JAM - 2009
SYLLABUS FOR BIOTECHNOLOGY (BT) TEST PAPER
The Biotechnology (BT) test paper comprises of Biology (44% weightage), Chemistry (20% weightage), Mathematics (18% weightage) and Physics (18% weightage).
BIOLOGY (10+2+3 level)
General Biology: Taxonomy; Heredity; Genetic variation; Conservation; Principles of ecology; Evolution; Techniques in modern biology. Biochemistry and Physiology: Carbohydrates; Proteins; Lipids; Nucleic acids; Enzymes; Vitamins; Hormones; Metabolism; Photosynthesis. Nitrogen Fixation, Fertilization and Osmoregulation; Nervous system; Endocrine system; Vascular system; Immune system; Digestive system, Reproductive System. Basic Biotechnology: Tissue culture; Application of enzymes; Antigen-antibody interaction; Antibody production; Diagnostic aids. Molecular Biology: DNA; RNA; Replication; Transcription; Translation; Proteins; Lipids; Membranes; Gene transfer. Cell Biology: Cell cycle; Cytoskeletal elements; Mitochondria; Endoplasmic reticulum; chloroplast; Golgi apparatus; Signaling. Microbiology: Isolation; Cultivation; Characterization and enumeration of virus; Bacteria; Fungi; Protozoa; Pathogenic micro-organisms.
CHEMISTRY (10+2+3 level)
Atomic Structure: Bohr's theory and Schrodinger wave equation; Periodicity in properties; Chemical bonding; Properties of s, p, d and block elements; Complex formation; Coordination compounds; Chemical equilibria; Chemical thermodynamics (first and second law); Chemical kinetics (zero, first, second and third order reactions); Photochemistry; Electrochemistry; Acid-base concepts; Stereochemistry of carbon compounds; Inductive, Electromeric, conjugative effects and resonance; Chemistry of Functional Groups: hydrocarbons, alkyl halides, alcohols, aldehydes, ketones, carboxylic acids, amines and their derivatives; Aromatic hydrocarbons, halides, nitro and amino compounds, phenols, diazonium salts, carboxylic and sulphonic acids; Mechanism of organic reaction; Soaps and detergents; Synthetic polymers; Biomolecules - aminoacids, proteins, nucleic acids, lipids and carbohydrates (polysaccharides); Instrumental techniques-chromatography (TLC, HPLC), electrophoresis, UV-Vis-IR and NMR spectroscopy, mass spectrometry, etc.
MATHEMATICS (10+2 level)
Sets, Relations and Functions, Mathematical Induction, Logarithms, Complex numbers, Linear and Quadratic equations, Sequences and Series, Trignometry, Cartesian System of Rectangular Coordinates, Straight lines and Family, Circles, Conic Sections, Permutations and Combinations, Binomial Theorem, Exponential and Logarithmic Series, Mathematical Logic, Statistics, Three Dimensional Geometry, Vectors, Stocks, Shares and Debentures, Average and Partition Values, Index numbers, Matrices and Determinants, Boolean Algebra, Probability, Functions, limits and Continuity, Differentiation, Application of Derivatives, Definite and Indefinite Integrals, Differential Equations, Elementary Statics and Dynamics, Partnership, Bill of Exchange, Linear Programming, Annuities, Application of Calculus in Commerce and Economics.
PHYSICS (10+2 level)
Physical World and Measurement, Kinematics, Laws of Motion, Work, Energy and Power Electrostatics, Current electricity, Magnetic Effects of Current and Magnetism, Electromagnetic Induction and Alternating Current, Electromagnetics waves, Optics, Dual Nature of Matter and Radiations, Atomic Nucleus, Solids and Semiconductor Devices, Principles of Communication, Motion of System of Particles and Rigid Body, Gravitation, Mechanics of Solids and Fluids, Heat and Thermodynamics, Oscillations, Waves.
SYLLABUS FOR CHEMISTRY (CY) TEST PAPER
PHYSICAL CHEMISTRY
Basic Mathematical Concepts : Differential equations, vectors and matrices.
Atomic Structure: Fundamental particles. Bohr's theory of hydrogen atom; Wave-particle duality; Uncertainty principles; Schrodinger's wave equation; Quantum numbers, shapes of orbitals; Hund's rule and Pauli's exclusion principle.
Theory of Gases: Kinetic theory of gases. Maxwell-Boltzmann distribution law; Equipartition of energy.
Chemical Thermodynamics: Reversible and irreversible processes; First law and its application to ideal and nonideal gases; Thermochemistry ; Second law; Entropy and free energy, Criteria for spontaneity.
Chemical and Phase Equilibria: Law of mass action; K p , K c ,K x and K n ; Effect of temperature on K; Ionic equilibria in solutions; pH and buffer solutions; Hydrolysis; Solubility product; Phase equilibria�Phase rule and its application to one-component and two-component systems; Colligative properties.
Electrochemistry: Conductance and its applications; Transport number; Galvanic cells; EMF and Free energy; Concentration cells with and without transport; Polarography.
Chemical Kinetics : Reactions of various order, Arrhenius equation, Collision theory; Theory of absolute reaction rate; Chain reactions � Normal and branched chain reactions; Enzyme kinetics; Photophysical and photochemical processes; Catalysis.
ORGANIC CHEMISTRY
Basic Concepts in Organic Chemistry and Stereochemistry: Isomerism and nomenclature, electronic (resonance and inductive) effects. Optical isomerism in compounds containing one and two asymmetric centers, designation of absolute configuration, conformations of cyclohexanes.
Aromaticity and Huckel's rule: Mono and bicyclic aromatic hydrocarbons.
Organic Reaction Mechanism and Synthetic Applications: Methods of preparation and reactions of alkanes, alkenes, alkynes, arenes and their simple functional derivatives. Mechanism and synthetic applications of electrophilic aromatic substitution. Stereochemistry and mechanism of aliphatic nucleophilic substitution and elimination reactions. Mechanism of aldol condensation, Claisen condensation, esterification and ester hydrolysis, Cannizzaro reaction, benzoin condensation. Perkin reaction, Claisen rearrangement, Beckmann rearrangement and Wagner-Meerwein rearrangement. Synthesis of simple molecules using standard reactions of organic chemistry. Grignard reagents, acetoacetic and malonic ester chemistry.
Natural Products Chemistry: Introduction to the following classes of compounds-alkaloids, terpenes, carbohydrates, amino acids, peptides and nuclei acids.
Heterocyclic Chemistry: Monocyclic compounds with one hetero atom.
Qualitative Organic Analysis: Functional group interconversions, structural problems using chemical reactions, identification of functional groups by chemical tests.
INORGANIC CHEMISTRY
Periodic Table: Periodic classification of elements and periodicity in properties; general methods of isolation and purification of elements.
Chemical Bonding and Shapes of Compounds: Types of bonding; VSEPR theory and shapes of molecules; hybridization; dipole moment; ionic solids; structure of NaCl, CsCl, diamond and graphite; lattice energy.
Main Group Elements (s and p blocks): Chemistry with emphasis on group relationship and gradation in properties; structure of electron deficient compounds of main group elements and application of main group elements.
Transition Metals (d block): Characteristics of 3d elements; oxide, hydroxide and salts of first row metals; coordination complexes; VB and Crystal Field theoretical approaches for structure, colour and magnetic properties of metal complexes.
Analytical Chemistry: Principles of qualitative and quantitative analysis; acid-base, oxidation-reduction and precipitation reactions; use of indicators; use of organic reagents in inorganic analysis; radioactivity; nuclear reactions; applications of isotopes.
SYLLABUS FOR COMPUTER APPLICATIONS (CA) TEST PAPER
The Computer Applications (CA) test paper comprises of Mathematics, Computer awareness and Analytical ability and General awareness and they will be in the ration 4:2:1.
MATHEMATICS
Algebra: Set theory and its simple applications. Basic concepts of groups, fields and vector spaces.
Matrices: Rank of a matrix. Existence and uniqueness of solution of a system of linear equation. Eigenvalues and Eigenvectors. Inverse of a matrix by elementary transformations.
Differential Calculus: Differentiation, Partial differentiation, Taylor series and approximate calculations. Maxima and minima of functions of one and two variables.
Integral Calculus: Single and multiple integration. Definite integrals, Change of order and change of variables. Application to evaluation of area, surface and volume.
Differential Equations: First order differential equations, linear differential equations of higher order with constant coefficients.
Vector Analysis: Vector algebra, Gradient.
Numerical Analysis: Solution of non linear equations using iterative methods. Interpolation (Lagrange's formula and Newton 's formulae for equidistant points). Numerical differentiation and integration (Trapezoidal and Simpson's rules).
Probability: Basic concepts of probability theory. Binomial and Poisson distributions.
Linear Programming: Formulation and its graphical solution for two variable problems.
COMPUTER AWARENESS
Elements of computers. Number systems. Basic electronic gates. Boolean algebra. Flip-Flops. Algorithmic approach to solve problems. Fundamentals of C language.
ANALYTICAL ABILITY AND GENERAL AWARENESS
Simple questions will be asked to test the analytical ability and general awareness of candidates.
SYLLABUS FOR GEOLOGY (GG) TEST PAPER
The Planet Earth: Origin of the Solar System and the Earth; Geosphere and the composition of the Earth; Shape and size of the earth; Earth-moon system; Formation of continents and oceans; Dating rocks and age of the Earth; Energy in the earth system; Volcanism and volcanic land forms; Interior of earth; Earthquakes; Earth's magnetism and gravity, Isostasy; Elements of Plate tectonics; Orogenesis.
Geomorphology: Weathering and erosion; Transportation and deposition due to wind, ice, river, sea, and resulting landforms, Structurally controlled landforms.
Structural Geology: Concept of stratum; Contour; Outcrop patterns; Maps and cross sections; Dip and strike; Classification and origin of folds, faults, joints, foliation and lineation, unconformities; shear zones.
Palaeontology: Origin and evolution of life; Fossils; their mode of preservation and utility; Morphological characters and ages of important groups of animals; Brachiopoda, Mollusca, Trilobita, Graptolitoidea, Anthozoa, Echinodermata etc. Gondwana plant fossils; Elementary idea of verterbrate fossils in India .
Stratigraphy: Principles of stratigraphy; Classification, distribution and ages of the stratigraphic formations of India from Archaean to Recent.
Mineralogy: Symmetry and forms in common crystal classes; Physical properties of minerals; Isomorphism and polymorphism, Classification of minerals; Structure of silicates; Mineralogy of common rock-forming minerals; Mode of occurrence of minerals in rocks. Transmitted polarised light microscopy and optical properties of uniaxial and biaxial minerals.
Petrology: Definition and classification of rocks; Igneous rocks- forms of igneous bodies; Crystallization from magma; classification, association and genesis of igneous rocks; Sedimentary rocks - classification, texture and structure; size and shape of sedimentary bodies. Metamorphic rocks - classification, facies, texture and properties.
Economic Geology: Properties of common economic minerals; General processes of formation of mineral deposits; Physical characters; Mode of occurrence and distribution in India both of metallic and non-metallic mineral deposits; Coal and petroleum occurrences in India .
Applied Geology: Ground Water; Mineral exploration, elements of mining and environmental geology; Principles of engineering geology.
SYLLABUS FOR GEOPHYSICS (GP) TEST PAPER
There will be Three sections in the Geophysics (GP) test paper, namely, Geology, Mathematics and Physics, each with a weightage of 50%. A candidate has to attempt any Two sections.
The syllabus for the Geology, Mathematics and Physics Sections of the Geophysics (GP) test paper are given below:
GEOLOGY SECTION
The Planet Earth: Origin of the Solar System and the Earth; Geosphere and the composition of the earth; Shape and size of the Earth; Earth-moon system; Formation of continents and oceans; dating the rocks and age of the Earth; Energy in the earth system; Volcanism and volcanic land forms; Interior of earth; Earthquakes and seismic waves; Earth's magnetism and gravity, Isostasy; Elements of plate tectonics; Orogenesis.
Geomorphology: Weathering and erosion; transportation and deposition due to wind, ice, river, sea, and resulting landforms, Structurally controlled landforms.
Structural Geology: Concept of stratum; Contour; Outcrop patterns; Maps and cross sections; Dip and strike; classification and origin of folds, faults, joints, foliation and lineation, unconformities; shear zones.
Mineralogy: Symmetry and forms in common crystal classes; physical properties of minerals; Isomorphism and polymorphism, Classification of minerals; Structure of silicates; Mineralogy of common rock-forming minerals; Mode of occurrence of minerals in rock.
Stratigraphy: Principles of Stratigraphy, Geological Time Scale, ages of major stratigraphic units of India.
Petrology: Definition and classification of rocks; Igneous rock-forms of igneous bodies; Crystallisation from magma; classification and association of igneous rocks; Principles of Stratigraphy; Sedimentary rocks-classification, texture and structure; Metamorphic rocks-Classification, facies, texture and structure.
Economic Geology: Physical properties of common ore minerals, General processes of formation of mineral deposits; Mode of occurrence of important metallic and non-metallic deposits in India; Coal, petroleum and ground water occurrences in India.
MATHEMATICS SECTION
Sequences, Series and Differential Calculus: Sequences of real numbers, Convergent sequences and series. Mean Value Theorem, Taylor 's theorem, Maxima and Minima, functions of several variables.
Integral Calculus: Fundamental theorem of calculus, Integration, Double and Triple integrals, Surface Areas and Volumes.
Differential Equations: Linear and Non-linear ODE, existence and uniqueness (without proof), Linear Differential Equations of second order with constant coefficients.
Vector Calculus: Gradient, Divergence, Curl, Laplacian, Green's, Strokes and Gauss theorems and their Applications.
Linear Algebra: System of Linear Equations, Matrices, Rank, Determinant, Inverse, eigen-values and eigen-vectros. Dimension, Linear transformations.
Real Analysis: Open and closed sets and limit points in R and completeness in R , Uniform Continuity, Power Series, Uniform Convergence.
Probability: Probability spaces, Conditional Probability, Independence , Bayes Theorem, Univariate and Bivariate Random Variables, Moment Generating and Characteristic Functions, Binomial, Poisson and Normal distributions.
Statistics: Sampling Distributions of Sample Mean and Variance, Exact Sampling Distribution (Normal Population), Simple and Composite hypothesis, Best critical region of a Test, Neyman-Pearson theorem, Likelihood Ratio Testing and its Application to Normal population, comparison of normal populations, large sample theory of test of hypothesis, approximate test on the parameter of a binomial population, comparison of two binomial populations.
Complex Analysis: Analytical functions, Harmonic functions, Cauchy's theorem, Cauchy's Integral Formula, Taylor and Laurent Expansion, Poles and Residues.
Numerical Analysis: Difference table, symbolic operators, differences of a factorial, representation of a polynomial by factorials, Forward, backward and central difference approximation formulae. Simpson's one-third rule and the error in it, Gauss-Siedel method and method of elimination for numerical solution of a system of linear equations, iteration method and its convergence, Gradient and Newton-Raphson method and their convergence.
PHYSICS SECTION
Mechanics and General Properties of Matter: Newton 's laws of motion and applications, Kepler's laws, Gravitational Law and field, Conservative and non-conservative forces. System of particles, Centre of mass, equation of motion of the CM, conservation of linear and angular momentum, conservation of energy. Elastic and inelastic collisions. Rigid body motion, fixed axis rotations, rotation and translation, moments of Inertia and products of Inertia. Principal moments and axes. Elasticity, Hooke's law and elastic constants of isotropic solid, stress energy. Kinematics of moving fluids, equation of continuity, Euler's equation, Bernoulli's theorem, viscous fluids, surface tension and surface energy, capillarity.
Oscillations, Waves and Optics: Differential equation for simple harmonic oscillator and its general solution. Superposition of two or more simple harmonic oscillators. Lissajous figures. Damped and forced oscillators, resonance. Wave equation, traveling and standing waves in one-dimension. Energy density and energy transmission in waves. Group velocity and phase velocity. Sound waves in media. Doppler Effect. Fermat's Principle. General theory of image formation. Thick lens, thin lens and lens combinations. Interference of light, optical path retardation. Fraunhofer diffraction. Rayleigh criterion and resolving power. Diffraction gratings. Polarization: linear, circular and elliptic polarization. Double refraction and optical rotation.
Electricity and Magnetism: Coulomb's law, Gauss's law. Concept of Potential, Field and Boundary Conditions, Solution of Laplace's equation for simple cases. Conductors, capacitors, dielectrics, dielectric polarization, volume and surface charges, electrostatic energy. Magnetic susceptibility, Bar magnet, Earth's magnetic field and its elements. Biot-Savart law, Ampere's law, Lenzes law, Faraday's law of electromagnetic induction, Self and mutual inductance. Alternating currents. Simple DC and AC circuits with R, L and C components. Displacement current, Maxwell's equations and plane electromagnetic waves. Lorentz Force and motion of charged particles in electric and magnetic fields.
Kinetic theory, Thermodynamics: Elements of Kinetic theory of gases. Velocity distribution and Equipartition of energy. Specific heat of Mono-, di- and tri-atomic gases. Ideal gas, Van-der-Waals gas and equation of state. Mean free path. Laws of thermodynamics. Zeroeth law and concept of thermal equilibrium. First law of thermodynamics and its consequences. Isothermal and adiabatic processes. Reversible, irreversible and quasi-static processes. Second law of thermodynamics. Carnot cycle.
Modern Physics: Blackbody radiation, photoelectric effect, Bohr's atomic model, X-rays. Wave-particle duality, Uncertainty principle, Pauli exclusion principle, Structure of atomic nucleus, mass and binding energy. Radioactivity and its applications. Laws of radioactive decay and half life, Fission and fusion
Solid State Physics, Devices and Electronics: Crystal structure, Bravais lattices and basis. Miller indices. X-ray diffraction and Bragg's law, Origin of energy bands. Concept of holes. Intrinsic and extrinsic semiconductors. p-n junctions, transistors. Amplifier circuits with transistors.
SYLLABUS FOR MATHEMATICAL STATISTICS (MS) TEST PAPER
The Mathematical Statistics (MS) test paper comprises of Mathematics (40% weightage) and Statistics (60% weightage).
Mathematics:
Sequences and Series: Convergence of sequences of real numbers, Comparison, root and ratio tests for convergence of series of real numbers.
Differential Calculus: Limits, continuity and differentiability of functions of one and two variables. Rolle's theorem, mean value theorems, Taylor 's theorem, indeterminate forms, maxima and minima of functions of one and two variables.
Integral Calculus: Fundamental theorems of integral calculus. Double and triple integrals, applications of definite integrals, arc lengths, areas and volumes.
Matrices: Rank, inverse of a matrix. systems of linear equations. Linear transformations, eigenvalues and eigenvectors. Cayley-Hamilton theorem, symmetric, skew-symmetric and orthogonal matrices.
Differential Equations: Ordinary differential equations of the first order of the form y' = f(x,y). Linear differential equations of the second order with constant coefficients.
Statistics:
Probability: Axiomatic definition of probability and properties, conditional probability, multiplication rule. Theorem of total probability. Bayes's theorem and independence of events.
Random Variables: Probability mass function, probability density function and cumulative distribution functions, distribution of a function of a random variable. Mathematical expectation, moments and moment generating function. Chebyshev's inequality.
Standard Distributions: Binomial, negative binomial, geometric, Poisson, hypergeometric, uniform, exponential, gamma, beta and normal distributions. Poisson and normal approximations of a binomial distribution.
Joint Distributions: Joint, marginal and conditional distributions. Distribution of functions of random variables. Product moments, correlation, simple linear regression. Independence of random variables.
Sampling distributions: Chi-square, t and F distributions, and their properties.
Limit Theorems: Weak law of large numbers. Central limit theorem (i.i.d.with finite variance case only).
Estimation: Unbiasedness, consistency and efficiency of estimators, method of moments and method of maximum likelihood. Sufficiency, factorization theorem. Completeness, Rao-Blackwell and Lehmann-Scheffe theorems, uniformly minimum variance unbiased estimators. Rao-Cramer inequality. Confidence intervals for the parameters of univariate normal, two independent normal, and one parameter exponential distributions.
Testing of Hypotheses: Basic concepts, applications of Neyman-Pearson Lemma for testing simple and composite hypotheses. Likelihood ratio tests for parameters of univariate normal distribution.
SYLLABUS FOR MATHEMATICS (MA) TEST PAPER
Sequences, Series and Differential Calculus : Sequences of real numbers. Convergent sequences and series, absolute and conditional convergence. Mean value theorem. Taylor 's theorem. Maxima and minima of functions of a single variable. Functions of two and three variables. Partial derivatives, maxima and minima.
Integral Calculus : Integration, Fundamental theorem of calculus. Double and Triple, integrals, Surface areas and volumes.
Differential Equations : Ordinary differential equations of the first order of the form y'=f(x,y). Linear differential equations of second order with constant coefficients. Euler-Cauchy equation. Method of variation of parameters.
Vector Calculus : Gradient, divergence, curl and Laplacian. Green's, Stokes' and Gauss' theorems and their applications.
Algebra : Groups, subgroups and normal subgroups, Lagrange's Theorem for finite groups, group homomorphisms and basic concepts of quotient groups, rings, ideals, quotient rings and fields.
Linear Algebra : Systems of linear equations. Matrices, rank, determinant, inverse. Eigenvalues and eigenvectors. Finite Dimensional Vector Spaces over Real and Complex Numbers, Basis, Dimension, Linear Transformations.
Real Analysis : Open and closed sets, limit points, completeness of R, Uniform Continuity, Uniform convergence, Power series.
SYLLABUS FOR PHYSICS (PH) TEST PAPER
Mathematical Methods: Calculus of single and multiple variables, partial derivatives, Jacobian, imperfect and perfect differentials, Taylor expansion, Fourier series. Vector algebra, Vector Calculus, Multiple integrals, Divergence theorem, Green's theorem, Stokes' theorem. First and linear second order differential equations. Matrices and determinants, Algebra of complex numbers.
Mechanics and General Properties of Matter: Newton's laws of motion and applications, Velocity and acceleration in Cartesian, polar and cylindrical coordinate systems, uniformly rotating frame, centrifugal and Coriolis forces, Motion under a central force, Kepler's laws, Gravitational Law and field, Conservative and non-conservative forces. System of particles, Centre of mass, equation of motion of the CM, conservation of linear and angular momentum, conservation of energy, variable mass systems. Elastic and inelastic collisions. Rigid body motion, fixed axis rotations, rotation and translation, moments of Inertia and products of Inertia. Principal moments and axes. Elasticity, Hooke's law and elastic constants of isotropic solid, stress energy. Kinematics of moving fluids, equation of continuity, Euler's equation, Bernoulli's theorem, viscous fluids, surface tension and surface energy, capillarity.
Oscillations, Waves and Optics: Differential equation for simple harmonic oscillator and its general solution. Superposition of two or more simple harmonic oscillators. Lissajous figures. Damped and forced oscillators, resonance. Wave equation, traveling and standing waves in one-dimension. Energy density and energy transmission in waves. Group velocity and phase velocity. Sound waves in media. Doppler Effect. Fermat's Principle. General theory of image formation. Thick lens, thin lens and lens combinations. Interference of light, optical path retardation. Fraunhofer diffraction. Rayleigh criterion and resolving power. Diffraction gratings. Polarization: linear, circular and elliptic polarization. Double refraction and optical rotation.
Electricity and Magnetism: Coulomb's law, Gauss's law. Electric field and potential. Electrostatic boundary conditions, Solution of Laplace's equation for simple cases. Conductors, capacitors, dielectrics, dielectric polarization, volume and surface charges, electrostatic energy. Biot-Savart law, Ampere's law, Faraday's law of electromagnetic induction, Self and mutual inductance. Alternating currents. Simple DC and AC circuits with R, L and C components. Displacement current, Maxwell's equations and plane electromagnetic waves, Poynting's theorem, reflection and refraction at a dielectric interface, transmission and reflection coefficients (normal incidence only). Lorentz Force and motion of charged particles in electric and magnetic fields.
Kinetic theory, Thermodynamics: Elements of Kinetic theory of gases. Velocity distribution and Equipartition of energy. Specific heat of Mono-, di- and tri-atomic gases. Ideal gas, van-der-Waals gas and equation of state. Mean free path. Laws of thermodynamics. Zeroeth law and concept of thermal equilibrium. First law and its consequences. Isothermal and adiabatic processes. Reversible, irreversible and quasi-static processes. Second law and entropy. Carnot cycle. Maxwell's thermodynamic relations and simple applications. Thermodynamic potentials and their applications. Phase transitions and Clausius-Clapeyron equation.
Modern Physics: Inertial frames and Galilean invariance. Postulates of special relativity. Lorentz transformations. Length contraction, time dilation. Relativistic velocity addition theorem, mass energy equivalence. Blackbody radiation, photoelectric effect, Compton effect, Bohr's atomic model, X-rays. Wave-particle duality, Uncertainty principle, Schrödinger equation and its solution for one, two and three dimensional boxes. Reflection and transmission at a step potential, tunneling through a barrier. Pauli exclusion principle. Distinguishable and indistinguishable particles. Max-well-Boltzmann, Fermi-Dirac and Bose-Einstein statistics. Structure of atomic nucleus, mass and binding energy. Radioactivity and its applications. Laws of radioactive decay. Fission and fusion.
Solid State Physics, Devices and Electronics: Crystal structure, Bravais lattices and basis. Miller indices. X-ray diffraction and Bragg's law, Einstein and Debye theory of specific heat. Free electron theory of metals. Fermi energy and density of states. Origin of energy bands. Concept of holes and effective mass. Elementary ideas about dia-, para- and ferromagnetism, Langevin's theory of paramagnetism, Curie's law. Intrinsic and extrinsic semiconductors. Fermi level. p-n junctions, transistors. Transistor circuits in CB, CE, CC modes. Amplifier circuits with transistors. Operational amplifiers. OR, AND, NOR and NAND gates.
Monday, May 25, 2009
Chemistry Olympiad Info
Chemistry
Stages
Stage I: National Standard Examination in Chemistry (NSEC)
Eligibility:
Syllabus:
Question Paper:
Qualifying for the Second Stage:
The International Chemistry Olympiad (IChO) has been conducted since 1968, and is a competition for
students at the secondary and higher secondary school levels. The IChO helps develop friendly relations
between the young people from different countries, and thus encourages co-operation and international
understanding. India started participating in this event from the year 1999 at the 31st IChO held at Bangkok,
Thailand. India hosted the 33rd International Chemistry Olympiad (IChO) in its third year of participation in
2001 with the whole-hearted support of all countries.
To know the five stage process of this program click on .
The chemistry Olympiad program follows the following 5 stages:
Stage I: National Standard Examination in Chemistry (NSEC),
Stage II: Indian National Chemistry Olympiad (INChO),
Stage III: Orientation cum Selection Camp (OCSC) in chemistry,
Stage IV: Pre-departure Training Camp (PDT) for IChO,
Stage V: Participation in International Chemistry Olympiad (IChO).
Stage 1 is entirely the responsibility of IAPT. All the remaining stages are organized by the HBCSE.
The detailed information about eligibility and structure of the stages is given below:
NSEC is the first stage of selection of students in the chemistry Olympiad Programme which is organised by
the Indian Association of Physics Teachers (IAPT). Every student aspiring to go through successive stages of
the programme must for NSEC. NSEC will be held at a large number of in the country.
Date and Time of NSEC 2008: 23 November2008 (Sunday) 12:30 pm to 02:30 pm
Last Date forEnrollment forNSEC: 15th September 2008
All Indian students of Class XI or Class XII (Science stream) and born after December 31, 1989 are eligible to
appear for NSEC. Astudent may appear for more than one subject provided the examination schedule allows it.
See information about the examination schedule under various subjects. Students who have passed Class XII
are not eligible to enroll for NSEC 2008.
It is the student's responsibility to ensure that the eligibility criteria are satisfied. In case at any stage of the
program it is found that the student does not satisfy the eligibility criteria, he/she may be disqualified from the
program.
The syllabus for NSEC is broadly equivalent to the senior secondary level (Class XI and Class XII) of CBSE
Chemistry. This is only a rough guideline, and there is no detailed syllabus given for NSEC.
NSEC emphasizes comprehension of the subject, not rote memory. Its format will be as follows:
The question paper will consist of 80 multiple choice questions, each with only one of the four options correct
(negative marks for incorrect answers). Total marks 240.
Language : English.
Based on performance in NSEC, the top 300 students in order of merit will qualify to appear for the Second
Stage of the Olympiad program (INChO). In case there is a tie at the last position, all additional students with
the same marks will also qualify for INChO 2009.
All students who qualify to appear for INChO 2009, will get a certificate of merit from IAPT.
Stages
enroll centres
Physics-Olympiads
Stage IV: Pre-departure Training (PDT) Camp for IChO
Stage V: Participation in International Chemistry Olympiad (IChO)
The selected 4 member Indian team undergoes a rigorous training programme at HBCSE in theory and
experiment. Special laboratories have been developed at HBCSE for the purpose. Resource persons from
HBCSE and different institutions across the country are invited to train the students. The duration of training
will be subject to IChO regulations.
The 4 member student team, 2 teacher leaders and 1 scientific observer constitute the delegation to represent
India at the International Chemistry Olympiad (IChO). The 41st IChO is to be held in London, UK
tentatively in July 2009.
Syllabus for International Chemistry Olympiad (IChO)
Syllabus for Theoretical Component of IChO ---
Syllabus for the Experimental Component of IChO ---
Please note:
·The syllabus for National Standard Examination in Chemistry (NSEC) is broadly equivalent to the
senior secondary level (Class XI and Class XII) of CBSE Chemistry. This is only a rough guideline,
and there is no detailed syllabus given for NSEC.
·The syllabus for Indian National Chemistry Olympiad (INChO) is broadly similar to NSEC but the
difficulty level of the questions will be higher. Questions and problems in National Olympiads are
usually non-conventional and of high difficulty level, comparable to International Olympiads
http://www.icho.sk/Icho_Syllabus_C_(2004).pdf
http://www.icho.sk/Append_d.doc
Sample Papers for INChO
INChO 2008
Published Books
1. INChO Theory Papers (2002 - 2007) by Dr. Savita Ladage and Ms. Swapna Narvekar
This book can be purchased from
In-Charge,
HBCSE Publications Section,
Homi Bhabha Centre for Science Education,
Tata Institute of Fundamental Research,
V. N. Purav Marg, Mankhurd,
Mumbai - 400088. India
Price: Rs. 150/- (for cash purchases made in person at HBCSE)
This book can also be purchased by sending a Demand Draft of Rs. 190/- (which includes postage charges
for registered parcel) in favour of Homi Bhabha Centre for Science Education, payable at Mumbai and sent
to the address above.
REFERENCE BOOKS FOR INCHO EXAMINATION
REFERENCE BOOKS FOR PRACTICAL CHEMISTRY
Suggested references that will be useful in preparing for the theory examinations of the Indian National
Chemistry Olympiad are given here. These books are usually available in most college libraries. You may
also consult your teachers for further guidance and choice of books.
a) Physical Chemistry
Maron & Prutton, Principles of Physical Chemistry, 4th Edition, Oxford and IBH Pub. Co. Pvt. Ltd.,
New Delhi/Calcutta.
Atkins P.W., Physical Chemistry, 5th Edition, Oxford University Press.
b) Organic Chemistry
Morrison & Boyd, Organic Chemistry, 6th Edition, Prentice Hall of India Pvt. Ltd., New Delhi.
Carey, Organic Chemistry, 3rd Edition, The McGraw-Hill Companies, Inc.
Atkins & Carey, Organic Chemistry- a brief course, 2nd Edition, The McGraw-Hill Companies,
Inc.
c) Inorganic Chemistry
Lee, Concise Inorganic Chemistry, 5th Edition, ELBS with Chapman & Hall.
Cotton, Wilkinson & Gaus, Basic Inorganic Chemistry, 3rd Edition, John Wiley & Sons.
d) Analytical Chemistry
Christian, Analytical Chemistry, 5th Edition, John Wiley & Sons, Inc.
Skoog & West, Fundamentals of Analytical Chemistry, 2nd Edition, Holt International Edition.
Skoog, Principles of Instrumental Analysis, 3rd Edition, Holt-Saunders International Edition.
e) Biochemistry
Lehninger, Principles of Biochemistry , CBS publishers and distributors Pvt. Ltd., Delhi (chapters
on amino acids, proteins, carbohydrates, and lipids)
Mckee & Mckee, Biochemistry an Introduction, 2nd Edition, WCB/McGraw-Hill.
f) General Chemistry
Mahan, University Chemistry, 3rd Edition, Narosa Publishing House.
Ebbing, General Chemistry, 3rd Edition, Houghton Mifflin Company, Boston.
Schaum series books on problems in various disciplines of chemistry.
Jeffrey, Bassett, Mendham & Denney, Vogel's Textbook of Quantitative Chemical Analysis, 5th Edition,
ELBS with Longman.
Arthur I.Vogel, Elementary Practical Organic Chemistry (Part 1, 2 and 3), CBS Publishers and
Distributors, Delhi.
Addison Ault, Techniques and Experiments for Organic Chemistry, 6th Edition, University Science Books,
Sausalito, California.
Day & Underwood, Quantitative Analysis, 5th Edition, Prentice Hall of India Pvt. Ltd., New Delhi.
CBSE practical books
Stages
Stage I: National Standard Examination in Chemistry (NSEC)
Eligibility:
Syllabus:
Question Paper:
Qualifying for the Second Stage:
The International Chemistry Olympiad (IChO) has been conducted since 1968, and is a competition for
students at the secondary and higher secondary school levels. The IChO helps develop friendly relations
between the young people from different countries, and thus encourages co-operation and international
understanding. India started participating in this event from the year 1999 at the 31st IChO held at Bangkok,
Thailand. India hosted the 33rd International Chemistry Olympiad (IChO) in its third year of participation in
2001 with the whole-hearted support of all countries.
To know the five stage process of this program click on .
The chemistry Olympiad program follows the following 5 stages:
Stage I: National Standard Examination in Chemistry (NSEC),
Stage II: Indian National Chemistry Olympiad (INChO),
Stage III: Orientation cum Selection Camp (OCSC) in chemistry,
Stage IV: Pre-departure Training Camp (PDT) for IChO,
Stage V: Participation in International Chemistry Olympiad (IChO).
Stage 1 is entirely the responsibility of IAPT. All the remaining stages are organized by the HBCSE.
The detailed information about eligibility and structure of the stages is given below:
NSEC is the first stage of selection of students in the chemistry Olympiad Programme which is organised by
the Indian Association of Physics Teachers (IAPT). Every student aspiring to go through successive stages of
the programme must for NSEC. NSEC will be held at a large number of in the country.
Date and Time of NSEC 2008: 23 November2008 (Sunday) 12:30 pm to 02:30 pm
Last Date forEnrollment forNSEC: 15th September 2008
All Indian students of Class XI or Class XII (Science stream) and born after December 31, 1989 are eligible to
appear for NSEC. Astudent may appear for more than one subject provided the examination schedule allows it.
See information about the examination schedule under various subjects. Students who have passed Class XII
are not eligible to enroll for NSEC 2008.
It is the student's responsibility to ensure that the eligibility criteria are satisfied. In case at any stage of the
program it is found that the student does not satisfy the eligibility criteria, he/she may be disqualified from the
program.
The syllabus for NSEC is broadly equivalent to the senior secondary level (Class XI and Class XII) of CBSE
Chemistry. This is only a rough guideline, and there is no detailed syllabus given for NSEC.
NSEC emphasizes comprehension of the subject, not rote memory. Its format will be as follows:
The question paper will consist of 80 multiple choice questions, each with only one of the four options correct
(negative marks for incorrect answers). Total marks 240.
Language : English.
Based on performance in NSEC, the top 300 students in order of merit will qualify to appear for the Second
Stage of the Olympiad program (INChO). In case there is a tie at the last position, all additional students with
the same marks will also qualify for INChO 2009.
All students who qualify to appear for INChO 2009, will get a certificate of merit from IAPT.
Stages
enroll centres
Physics-Olympiads
Stage IV: Pre-departure Training (PDT) Camp for IChO
Stage V: Participation in International Chemistry Olympiad (IChO)
The selected 4 member Indian team undergoes a rigorous training programme at HBCSE in theory and
experiment. Special laboratories have been developed at HBCSE for the purpose. Resource persons from
HBCSE and different institutions across the country are invited to train the students. The duration of training
will be subject to IChO regulations.
The 4 member student team, 2 teacher leaders and 1 scientific observer constitute the delegation to represent
India at the International Chemistry Olympiad (IChO). The 41st IChO is to be held in London, UK
tentatively in July 2009.
Syllabus for International Chemistry Olympiad (IChO)
Syllabus for Theoretical Component of IChO ---
Syllabus for the Experimental Component of IChO ---
Please note:
·The syllabus for National Standard Examination in Chemistry (NSEC) is broadly equivalent to the
senior secondary level (Class XI and Class XII) of CBSE Chemistry. This is only a rough guideline,
and there is no detailed syllabus given for NSEC.
·The syllabus for Indian National Chemistry Olympiad (INChO) is broadly similar to NSEC but the
difficulty level of the questions will be higher. Questions and problems in National Olympiads are
usually non-conventional and of high difficulty level, comparable to International Olympiads
http://www.icho.sk/Icho_Syllabus_C_(2004).pdf
http://www.icho.sk/Append_d.doc
Sample Papers for INChO
INChO 2008
Published Books
1. INChO Theory Papers (2002 - 2007) by Dr. Savita Ladage and Ms. Swapna Narvekar
This book can be purchased from
In-Charge,
HBCSE Publications Section,
Homi Bhabha Centre for Science Education,
Tata Institute of Fundamental Research,
V. N. Purav Marg, Mankhurd,
Mumbai - 400088. India
Price: Rs. 150/- (for cash purchases made in person at HBCSE)
This book can also be purchased by sending a Demand Draft of Rs. 190/- (which includes postage charges
for registered parcel) in favour of Homi Bhabha Centre for Science Education, payable at Mumbai and sent
to the address above.
REFERENCE BOOKS FOR INCHO EXAMINATION
REFERENCE BOOKS FOR PRACTICAL CHEMISTRY
Suggested references that will be useful in preparing for the theory examinations of the Indian National
Chemistry Olympiad are given here. These books are usually available in most college libraries. You may
also consult your teachers for further guidance and choice of books.
a) Physical Chemistry
Maron & Prutton, Principles of Physical Chemistry, 4th Edition, Oxford and IBH Pub. Co. Pvt. Ltd.,
New Delhi/Calcutta.
Atkins P.W., Physical Chemistry, 5th Edition, Oxford University Press.
b) Organic Chemistry
Morrison & Boyd, Organic Chemistry, 6th Edition, Prentice Hall of India Pvt. Ltd., New Delhi.
Carey, Organic Chemistry, 3rd Edition, The McGraw-Hill Companies, Inc.
Atkins & Carey, Organic Chemistry- a brief course, 2nd Edition, The McGraw-Hill Companies,
Inc.
c) Inorganic Chemistry
Lee, Concise Inorganic Chemistry, 5th Edition, ELBS with Chapman & Hall.
Cotton, Wilkinson & Gaus, Basic Inorganic Chemistry, 3rd Edition, John Wiley & Sons.
d) Analytical Chemistry
Christian, Analytical Chemistry, 5th Edition, John Wiley & Sons, Inc.
Skoog & West, Fundamentals of Analytical Chemistry, 2nd Edition, Holt International Edition.
Skoog, Principles of Instrumental Analysis, 3rd Edition, Holt-Saunders International Edition.
e) Biochemistry
Lehninger, Principles of Biochemistry , CBS publishers and distributors Pvt. Ltd., Delhi (chapters
on amino acids, proteins, carbohydrates, and lipids)
Mckee & Mckee, Biochemistry an Introduction, 2nd Edition, WCB/McGraw-Hill.
f) General Chemistry
Mahan, University Chemistry, 3rd Edition, Narosa Publishing House.
Ebbing, General Chemistry, 3rd Edition, Houghton Mifflin Company, Boston.
Schaum series books on problems in various disciplines of chemistry.
Jeffrey, Bassett, Mendham & Denney, Vogel's Textbook of Quantitative Chemical Analysis, 5th Edition,
ELBS with Longman.
Arthur I.Vogel, Elementary Practical Organic Chemistry (Part 1, 2 and 3), CBS Publishers and
Distributors, Delhi.
Addison Ault, Techniques and Experiments for Organic Chemistry, 6th Edition, University Science Books,
Sausalito, California.
Day & Underwood, Quantitative Analysis, 5th Edition, Prentice Hall of India Pvt. Ltd., New Delhi.
CBSE practical books
Thursday, May 14, 2009
ConcepTest on Enthalpy:
This is a series of ConcepTest questions on enthalpy, heat transfers, heat of reaction. It is best to
present them (or at least a section of them) in sequence.
Enthalpy, H, is often referred to as “heat content”.
If an object feels hot, it means...
1. it has a large enthalpy.
2. it has a low enthalpy.
3. Whether the object feels hot or not is unrelated to its enthalpy.
4. I don’t know.
Correct Answer: 3. Whether the object feels hot is unrelated to its enthalpy.
Comment to Instructor: Students tend to think that a high heat content must mean the object is hot.
They are confusing heat with temperature. Explain to the students that enthalpy is the potential to give
off heat. It does not mean the object is hot. Then go on to the next question.
∆H is defined as Hfinal − Hinitial.
If an object feels hot, it means it is undergoing a change with a ∆H that is...
1. positive.
2. negative.
Whether the object feels hot or not is unrelated to its ∆H.
3.
4. I don’t know.
Correct Answer: #2. negative.
Comment to Instructor: Students who choose #1 are probably thinking that if the object feels hot, it
must be absorbing heat, and so Hfinal would be larger than Hinitial.
Explain to the students that if the object feels hot, it is giving off heat, and so its enthalpy will become
smaller in the process. Thus Hfinal would be less than Hinitial, and ∆H would be negative. Then go on to
the next question.
If the object feels hot, it means it is undergoing...
1. an endothermic change.
2. an exothermic change.
3. Whether it feels hot or not is unrelated to whether it is undergoing endo- or exothermic
change.
Correct Answer: #2
Comment to Instructor: Some students may select #3 thinking that there is no change involved.
Clarify that change does not necessarily mean a chemical reaction. It can be simply a transfer of heat
from the object, such as a hot cup of coffee cooling down. Then explain that if it is giving off heat, it is
an exothermic change (#2.)
present them (or at least a section of them) in sequence.
Enthalpy, H, is often referred to as “heat content”.
If an object feels hot, it means...
1. it has a large enthalpy.
2. it has a low enthalpy.
3. Whether the object feels hot or not is unrelated to its enthalpy.
4. I don’t know.
Correct Answer: 3. Whether the object feels hot is unrelated to its enthalpy.
Comment to Instructor: Students tend to think that a high heat content must mean the object is hot.
They are confusing heat with temperature. Explain to the students that enthalpy is the potential to give
off heat. It does not mean the object is hot. Then go on to the next question.
∆H is defined as Hfinal − Hinitial.
If an object feels hot, it means it is undergoing a change with a ∆H that is...
1. positive.
2. negative.
Whether the object feels hot or not is unrelated to its ∆H.
3.
4. I don’t know.
Correct Answer: #2. negative.
Comment to Instructor: Students who choose #1 are probably thinking that if the object feels hot, it
must be absorbing heat, and so Hfinal would be larger than Hinitial.
Explain to the students that if the object feels hot, it is giving off heat, and so its enthalpy will become
smaller in the process. Thus Hfinal would be less than Hinitial, and ∆H would be negative. Then go on to
the next question.
If the object feels hot, it means it is undergoing...
1. an endothermic change.
2. an exothermic change.
3. Whether it feels hot or not is unrelated to whether it is undergoing endo- or exothermic
change.
Correct Answer: #2
Comment to Instructor: Some students may select #3 thinking that there is no change involved.
Clarify that change does not necessarily mean a chemical reaction. It can be simply a transfer of heat
from the object, such as a hot cup of coffee cooling down. Then explain that if it is giving off heat, it is
an exothermic change (#2.)
Friday, April 24, 2009
chemistry IIT JEE -2009 Analsyis
Maximum Marks = 160
Percentage (%)
Topic Marks
Inorganic Chemistry 37
58
Organic Chemistry 34
55
Physical Chemistry 29
47
Chemistry
2009
P-1 P-2
Topic
MM 80 80
Percentage (%) Percentage (%)
Physical Chemistry 16 20 31 38.75
Atomic Structure
Chemical Equilibrium
8.75
Chemical Kinetics & Radioactivity 7
5
Electrochemistry 4
3.75 5
Gaseous State 3 4
5
Ionic Equilibrium 4
5
Solid State 4
3.75
Solution & Colligative Peroperties 3
3.75 5
Stoichiometry (Mole-1, 2) 3 4
3.75
Surface Chemistry 3
10
Thermodynamics 8
Inorganic Chemistry 31 38.75 27 33.75
10 5
Chemical Bonding 8 4
5
Coordination Compounds 4
3.75
d-Block Elements & Compounds 3
Metallurgy
3.75 25
p-Block Elements & Compounds 3 20
Periodic Table & Periodicity in Properties
15
Qualitative Analysis 12
5
s-Block Elements & Compounds 4
Organic Chemistry 33 41.25 22 27.5
Alkane, Alkyl halide-GR - -
Alkenes & Alkynes
Aromatic Compound
5
Bio chemistry 4
15
Carbonyl Compounds 12
Carboxylic Acid and Derivatives
8.75 5
General Organic Chemistry-I 7 4
3.75 3.75
General Organic Chemistry-II 3 3
Partical Organic Chemistry
13.75 13.75
Reaction Mechanism 11 11
Percentage (%)
Topic Marks
Inorganic Chemistry 37
58
Organic Chemistry 34
55
Physical Chemistry 29
47
Chemistry
2009
P-1 P-2
Topic
MM 80 80
Percentage (%) Percentage (%)
Physical Chemistry 16 20 31 38.75
Atomic Structure
Chemical Equilibrium
8.75
Chemical Kinetics & Radioactivity 7
5
Electrochemistry 4
3.75 5
Gaseous State 3 4
5
Ionic Equilibrium 4
5
Solid State 4
3.75
Solution & Colligative Peroperties 3
3.75 5
Stoichiometry (Mole-1, 2) 3 4
3.75
Surface Chemistry 3
10
Thermodynamics 8
Inorganic Chemistry 31 38.75 27 33.75
10 5
Chemical Bonding 8 4
5
Coordination Compounds 4
3.75
d-Block Elements & Compounds 3
Metallurgy
3.75 25
p-Block Elements & Compounds 3 20
Periodic Table & Periodicity in Properties
15
Qualitative Analysis 12
5
s-Block Elements & Compounds 4
Organic Chemistry 33 41.25 22 27.5
Alkane, Alkyl halide-GR - -
Alkenes & Alkynes
Aromatic Compound
5
Bio chemistry 4
15
Carbonyl Compounds 12
Carboxylic Acid and Derivatives
8.75 5
General Organic Chemistry-I 7 4
3.75 3.75
General Organic Chemistry-II 3 3
Partical Organic Chemistry
13.75 13.75
Reaction Mechanism 11 11
Resonance
Resonance refers to structures that are not easily represented by a single electron dot structure but that are intermediates between two or more drawn structures.
Resonance is easily misunderstood in part because of the way certain chemistry textbooks attempt to explain the concept. In science, analogies can provide an aid to understanding, but analogies should not be taken too literally. It is sometimes best to use analogies to introduce a topic, but then explain the differences and inevitable complications as further details on a complicated subject. This is the case for resonance.
Just as entropic principles cannot be applied to individual molecules, so it is impossible to say whether or not any given individual molecule with a resonance structure is literally in one configuration or another. The actual situation on the molecular scale is that each configuration of the molecule contributes a percentage to the possible configurations, resulting in a "blend" of the possible structures. Changes in molecular shape occur so rapidly, and on such a tiny scale, that the actual physical locations of individual electrons cannot be precisely known (due to Heisenberg's Uncertainty Principle). The result of all that complexity is simply this: molecules with resonance structures are treated as mixtures of their multiple forms, with a greater percentage of probability given to the most stable configurations.
The nuclei of the atoms are not moving when they are represented by resonance structure drawings. Rather, the electrons are portrayed as if they were moving instead. The true situation is that no one can say for certain exactly where any individual electron is at any specific moment, but rather electron location can be expressed as a probability only. What a dot structure is actually showing is where electrons almost certainly are located, therefore resonance structures indicate a split in those same probabilities. Chemists are absolutely certain where electrons are located when one carbon bonds four hydrogens (methane), but it is less certain where precisely any given electron is located when six carbons bond six hydrogens in a ring structrue (benzene). Resonance is an expression of this uncertainty, and is therefore the average of probable locations.
Resonance structures are stabilizing in molecules because they allow electrons to lengthen their wavelengths and thereby lower their energy. This is the reason that benzene (C6H6) has a lower heat of formation than organic chemists would predict, not accounting for resonance. Other aromatic molecules have a similar stability, which leads to an overall entropic preference for aromaticity (a subject that will be covered fully in a later chapter). Resonance stability plays a major role in organic chemistry due to resonant molecules' lower energy of formation, so students of organic chemistry should understand this effect and practice spotting molecules stabilized by resonant forms.
Carbonate
In the Lewis structures above, carbonate (CO3) has a resonance structure. Using laboratory procedures to measure the bond length of each bond, we do not find that one bond is shorter than the two others (remember, double bonds are shorter than single bonds), but instead that all bonds are of the same length somewhere between the length of typical double and single bonds.
[edit] Resonance Structures
Scheme 1. Resonance structures of Benzene
Resonance structures are diagrammatic tools used predominately in organic chemistry to symbolize resonant bonds between atoms in molecules. The electron density of these bonds is spread over the molecule, also known as the delocalization of electrons. Resonance contributors for the same molecule all have the same chemical formula and same sigma framework, but the pi electrons will be distributed differently among the atoms. Because Lewis dot diagrams often cannot represent the true electronic structure of a molecule, resonance structures are often employed to approximate the true electronic structure. Resonance structures of the same molecule are connected with a double-headed arrow. While organic chemists use resonance structures frequently, they are used in inorganic structures, with nitrate as an example.
[edit] Key characteristics
The key elements of resonance are:
* Resonance occurs because of the overlap of orbitals. Double bonds are made up of pi bonds, formed from the overlap of 2p orbitals. The electrons in these pi orbitals will be spread over more than two atoms, and hence are delocalized.
* Both paired and unshared electrons may be delocalized, but all the electrons must be conjugated in a pi system.
* If the orbitals do not overlap (such as in orthogonal orbitals) the structures are not true resonance structures and do not mix.
* Molecules or species with resonance structures are generally considered to be more stable than those without them. The delocalization of the electrons lowers the orbital energies, imparting this stability. The resonance in benzene gives rise to the property of aromaticity. The gain in stability is called the resonance energy.
* All resonance structures for the same molecule must have the same sigma framework (sigma bonds form from the "head on" overlap of hybridized orbitals). Furthermore, they must be correct Lewis structures with the same number of electrons (and consequent charge) as well as the same number of unpaired electrons. Resonance structures with arbitrary separation of charge are unimportant, as are those with fewer covalent bonds. These unimportant resonance structures only contribute minimally (or not at all) to the overall bonding description; however, they are important in some cases such as for a carbonyl group.
* The hybrid structure is defined as the superposition of the resonance structures. A benzene ring is often shown with a circle inside a hexagon (in American texts) rather than alternating double bonds — the latter example misrepresents the electronic structure. Bonds with broken bond orders are often displayed as double bonds with one solid and one dashed line.
[edit] What resonance is not
Significantly, resonance structures do not represent different, isolatable structures or compounds. In the case of benzene, for example, there are two important resonance structures - which can be thought of as cyclohexa-1,3,5-trienes. There are other resonance forms possible, but because they are higher in energy than the triene structures (due to charge separation or other effects) they are less important and contribute less to the "real" electronic structure (average hybrid). However, this does not mean there are two different, interconvertable forms of benzene; rather, the true electronic structure of benzene is an average of the two structures. The six carbon-carbon bond lengths are identical when measured, which would be invalid for the cyclic triene. Resonance should also not be confused with a chemical equilibrium or tautomerism which are equilibria between compounds that have different sigma bonding patterns. Hyperconjugation is a special case of resonance.
[edit] History
The concept of resonance was introduced by Linus Pauling in 1928. He was inspired by the quantum mechanical treatment of the H2+ ion in which an electron is located between two hydrogen nuclei. The alternative term mesomerism popular in German and French publications with the same meaning was introduced by Christopher Ingold in 1938 but did not catch on in the English literature. The current concept of Mesomeric effect has taken on a related but different meaning. The double headed arrow was introduced by the German chemist Arndt (also responsible for the Arndt-Eistert synthesis) who preferred the German phrase zwischenstufe or intermediate phase.
Due to confusion with the physical meaning of the word resonance, as no elements do actually appear to be resonating, it is suggested to abandon the term resonance in favor of delocalization [1]. Resonance energy would become delocalization energy and a resonance structure becomes contributing structure. The double headed arrows would get replaced by commas.
[edit] Examples
Scheme 2. Examples of resonance ozone, benzene and the allyl cation
The ozone molecule is represented by two resonance structures in the top of scheme 2. In reality the two terminal oxygen atoms are equivalent and the hybrid structure is drawn on the right with a charge of -1/2 on both oxygen atoms and partial double bonds. The concept of benzene as a hybrid of two conventional structures (middle scheme 2) was a major breakthrough in chemistry made by Kekule, and the two forms of the ring which together represent the total resonance of the system are called Kekule structures. In the hybrid structure on the right the circle replaces three double bonds. The allyl cation (bottom scheme 2) has two resonance forms and in the hybrid structure the positive charge is delocalized over the terminal methylene groups.
In chemistry delocalized electrons are electrons in a molecule that are not associated with a single atom or to a covalent bond. Delocalized electrons are contained within an orbital that extends over several adjacent atoms. Classically, delocalized electrons can be found in conjugated systems of double bonds and in aromatic and mesoionic systems. A case of delocalized electrons occurs also in solid metals, where the d-subshell interferes with the above s-subshell, and contributes to the properties of a metal. It is increasingly appreciated that electrons in sigma bonding levels are also delocalized. For example, in methane, the bonding electrons are shared by all five atoms equally. Pervasive existence of delocalization is implicit in Molecular Orbital Theory.
In the simple aromatic ring of benzene the delocalization of six π electrons over the C6 ring is often graphically indicated by a circle. The fact that the six C-C bonds are equidistant is one indication of this delocalization. In Valence Bond Theory, delocalization in benzene is represented by resonance structures.
Another example of delocalized electrons can be found in a carboxylate group, wherein the negative charge is centered equally on the two oxygen atoms.
Delocalized electrons are important for several reasons. One, an expected chemical reaction may not occur because the electrons delocalize to a more stable configuration, resulting in a reaction that happens at a different location. An example attempting the Fridel-Crafts alkylation of benzene with 1-chloro-2-methylpropane; the carbocation rearranges to a tert-butyl group stabilized by hyperconjugation, a particular form of delocalization.
Delocalized electrons also exist in the structure of metals. Metallic structure consist of aligned positive ions (cations) in a "sea" of delocalized electrons. This means that the electrons are free to move throughout the structure, and gives rise to properties such as conductivity.
In diamond all four outer electrons of each carbon atom are 'localized' between the atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. The delocalized electrons are free to move throughout the plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct in a direction at right angles to the plane.
A conjugated system occurs in an organic compound where atoms covalently bond with alternating single and multiple (e.g. double) bonds (e.g., C=C-C=C-C) and influence each other to produce a region called electron delocalization. In this region electrons do not belong to a single bond or atom, but rather a group. For example, phenol (C6H5OH, benzene with hydroxyl group) (diagramatically has alternating single and double bonds), which has a system of 6 electrons above and below the flat planar ring, as well as around the hydroxyl group.
The conjugated system results in a general delocalization of the electrons across all of the adjacent parallel aligned p-orbitals of the atoms, which increases stability and thereby lowers the overall energy of the molecule [1].
Conjugation can be maintained by the presence of different kinds of p-orbital-donating groups. Furan is considered a conjugated system for this reason.
Conjugation is possible by means other than the presence of alternating single and double bonds. As long as each contiguous atom in a chain possesses a p-orbital, the system can be considered conjugated. For example, furan (shown at right) is a five-membered ring with two alternating double bonds and an oxygen in position 1. Oxygen has two lone pairs, one of which occupies a p-orbital on that position, thereby maintaining the conjugation of that five-membered ring. The presence of a nitrogen in the ring or groups α to the ring like a carbonyl group (C=O), an imine group (C=N), a vinyl group (C=C), or an anion will also suffice as a source of pi orbitals to maintain conjugation.
Conjugated systems have unique properties that give rise to strong colors. Many pigments make use of conjugated electron systems, such as beta-carotene's long conjugated hydrocarbon chain resulting in a strong orange color. When an electron in the system absorbs a photon of light of the right wavelength, it can be promoted to a higher energy level. (See particle in a box). Most of these electronic transitions are of a p-orbital electron to a p-antibonding orbital (π to π*), but non-bonding electrons can also be promoted (n to π*). Conjugated systems of fewer than eight conjugated double bonds absorb only in the ultraviolet region and are colorless to the human eye. With every double bond added, the system absorbs photons of longer wavelength (and lower energy), and the compound ranges from yellow to red in color. Compounds that are blue or green typically do not rely on conjugated double bonds alone.
This absorption of light in the ultraviolet to visible spectrum can be quantified using UV/VIS spectroscopy, and forms the basis for the entire field of photochemistry.
Chemical structure of beta-carotene. The eleven conjugated double bonds that form the chromophore of the molecule are highlighted in red.
Conjugated systems form the basis of chromophores, which are light-absorbing parts of a molecule which can cause a compound to be colored. Such chromophores are often present in various organic compounds and sometimes present in polymers, which are colored or glow in the dark. They are usually caused by conjugated ring systems with bonds such as C=O and N=N in addition to conjugated C-C bonds.
The native conformation of cyclooctatetraene. Adjacent double bonds are not coplanar, so there is not strong conjugation between them.
Conjugation in cyclic structures results in aromaticity, an unusual stability found in cyclic conjugated systems.
It is important to note that merely possessing alternating double and single bonds is not enough for a system to be strongly conjugated. Some cyclic hydrocarbons (such as cyclooctatetraene) do indeed possess alternating single and double bonds. Although the molecule may appear planar if one looks only at its chemical structure, it is in fact not, and typically adopts a "tub" conformation. Because the p-orbitals of the molecule do not align themselves well in this non-planar molecule, the electrons are not as easily shared between the carbon atoms. They can be still considered conjugated, but they are not considered antiaromatic (and also not aromatic; see Hückel's rule). Cyclooctatetraene would not be considered antiaromatic because it is not planar.
Resonance is easily misunderstood in part because of the way certain chemistry textbooks attempt to explain the concept. In science, analogies can provide an aid to understanding, but analogies should not be taken too literally. It is sometimes best to use analogies to introduce a topic, but then explain the differences and inevitable complications as further details on a complicated subject. This is the case for resonance.
Just as entropic principles cannot be applied to individual molecules, so it is impossible to say whether or not any given individual molecule with a resonance structure is literally in one configuration or another. The actual situation on the molecular scale is that each configuration of the molecule contributes a percentage to the possible configurations, resulting in a "blend" of the possible structures. Changes in molecular shape occur so rapidly, and on such a tiny scale, that the actual physical locations of individual electrons cannot be precisely known (due to Heisenberg's Uncertainty Principle). The result of all that complexity is simply this: molecules with resonance structures are treated as mixtures of their multiple forms, with a greater percentage of probability given to the most stable configurations.
The nuclei of the atoms are not moving when they are represented by resonance structure drawings. Rather, the electrons are portrayed as if they were moving instead. The true situation is that no one can say for certain exactly where any individual electron is at any specific moment, but rather electron location can be expressed as a probability only. What a dot structure is actually showing is where electrons almost certainly are located, therefore resonance structures indicate a split in those same probabilities. Chemists are absolutely certain where electrons are located when one carbon bonds four hydrogens (methane), but it is less certain where precisely any given electron is located when six carbons bond six hydrogens in a ring structrue (benzene). Resonance is an expression of this uncertainty, and is therefore the average of probable locations.
Resonance structures are stabilizing in molecules because they allow electrons to lengthen their wavelengths and thereby lower their energy. This is the reason that benzene (C6H6) has a lower heat of formation than organic chemists would predict, not accounting for resonance. Other aromatic molecules have a similar stability, which leads to an overall entropic preference for aromaticity (a subject that will be covered fully in a later chapter). Resonance stability plays a major role in organic chemistry due to resonant molecules' lower energy of formation, so students of organic chemistry should understand this effect and practice spotting molecules stabilized by resonant forms.
Carbonate
In the Lewis structures above, carbonate (CO3) has a resonance structure. Using laboratory procedures to measure the bond length of each bond, we do not find that one bond is shorter than the two others (remember, double bonds are shorter than single bonds), but instead that all bonds are of the same length somewhere between the length of typical double and single bonds.
[edit] Resonance Structures
Scheme 1. Resonance structures of Benzene
Resonance structures are diagrammatic tools used predominately in organic chemistry to symbolize resonant bonds between atoms in molecules. The electron density of these bonds is spread over the molecule, also known as the delocalization of electrons. Resonance contributors for the same molecule all have the same chemical formula and same sigma framework, but the pi electrons will be distributed differently among the atoms. Because Lewis dot diagrams often cannot represent the true electronic structure of a molecule, resonance structures are often employed to approximate the true electronic structure. Resonance structures of the same molecule are connected with a double-headed arrow. While organic chemists use resonance structures frequently, they are used in inorganic structures, with nitrate as an example.
[edit] Key characteristics
The key elements of resonance are:
* Resonance occurs because of the overlap of orbitals. Double bonds are made up of pi bonds, formed from the overlap of 2p orbitals. The electrons in these pi orbitals will be spread over more than two atoms, and hence are delocalized.
* Both paired and unshared electrons may be delocalized, but all the electrons must be conjugated in a pi system.
* If the orbitals do not overlap (such as in orthogonal orbitals) the structures are not true resonance structures and do not mix.
* Molecules or species with resonance structures are generally considered to be more stable than those without them. The delocalization of the electrons lowers the orbital energies, imparting this stability. The resonance in benzene gives rise to the property of aromaticity. The gain in stability is called the resonance energy.
* All resonance structures for the same molecule must have the same sigma framework (sigma bonds form from the "head on" overlap of hybridized orbitals). Furthermore, they must be correct Lewis structures with the same number of electrons (and consequent charge) as well as the same number of unpaired electrons. Resonance structures with arbitrary separation of charge are unimportant, as are those with fewer covalent bonds. These unimportant resonance structures only contribute minimally (or not at all) to the overall bonding description; however, they are important in some cases such as for a carbonyl group.
* The hybrid structure is defined as the superposition of the resonance structures. A benzene ring is often shown with a circle inside a hexagon (in American texts) rather than alternating double bonds — the latter example misrepresents the electronic structure. Bonds with broken bond orders are often displayed as double bonds with one solid and one dashed line.
[edit] What resonance is not
Significantly, resonance structures do not represent different, isolatable structures or compounds. In the case of benzene, for example, there are two important resonance structures - which can be thought of as cyclohexa-1,3,5-trienes. There are other resonance forms possible, but because they are higher in energy than the triene structures (due to charge separation or other effects) they are less important and contribute less to the "real" electronic structure (average hybrid). However, this does not mean there are two different, interconvertable forms of benzene; rather, the true electronic structure of benzene is an average of the two structures. The six carbon-carbon bond lengths are identical when measured, which would be invalid for the cyclic triene. Resonance should also not be confused with a chemical equilibrium or tautomerism which are equilibria between compounds that have different sigma bonding patterns. Hyperconjugation is a special case of resonance.
[edit] History
The concept of resonance was introduced by Linus Pauling in 1928. He was inspired by the quantum mechanical treatment of the H2+ ion in which an electron is located between two hydrogen nuclei. The alternative term mesomerism popular in German and French publications with the same meaning was introduced by Christopher Ingold in 1938 but did not catch on in the English literature. The current concept of Mesomeric effect has taken on a related but different meaning. The double headed arrow was introduced by the German chemist Arndt (also responsible for the Arndt-Eistert synthesis) who preferred the German phrase zwischenstufe or intermediate phase.
Due to confusion with the physical meaning of the word resonance, as no elements do actually appear to be resonating, it is suggested to abandon the term resonance in favor of delocalization [1]. Resonance energy would become delocalization energy and a resonance structure becomes contributing structure. The double headed arrows would get replaced by commas.
[edit] Examples
Scheme 2. Examples of resonance ozone, benzene and the allyl cation
The ozone molecule is represented by two resonance structures in the top of scheme 2. In reality the two terminal oxygen atoms are equivalent and the hybrid structure is drawn on the right with a charge of -1/2 on both oxygen atoms and partial double bonds. The concept of benzene as a hybrid of two conventional structures (middle scheme 2) was a major breakthrough in chemistry made by Kekule, and the two forms of the ring which together represent the total resonance of the system are called Kekule structures. In the hybrid structure on the right the circle replaces three double bonds. The allyl cation (bottom scheme 2) has two resonance forms and in the hybrid structure the positive charge is delocalized over the terminal methylene groups.
In chemistry delocalized electrons are electrons in a molecule that are not associated with a single atom or to a covalent bond. Delocalized electrons are contained within an orbital that extends over several adjacent atoms. Classically, delocalized electrons can be found in conjugated systems of double bonds and in aromatic and mesoionic systems. A case of delocalized electrons occurs also in solid metals, where the d-subshell interferes with the above s-subshell, and contributes to the properties of a metal. It is increasingly appreciated that electrons in sigma bonding levels are also delocalized. For example, in methane, the bonding electrons are shared by all five atoms equally. Pervasive existence of delocalization is implicit in Molecular Orbital Theory.
In the simple aromatic ring of benzene the delocalization of six π electrons over the C6 ring is often graphically indicated by a circle. The fact that the six C-C bonds are equidistant is one indication of this delocalization. In Valence Bond Theory, delocalization in benzene is represented by resonance structures.
Another example of delocalized electrons can be found in a carboxylate group, wherein the negative charge is centered equally on the two oxygen atoms.
Delocalized electrons are important for several reasons. One, an expected chemical reaction may not occur because the electrons delocalize to a more stable configuration, resulting in a reaction that happens at a different location. An example attempting the Fridel-Crafts alkylation of benzene with 1-chloro-2-methylpropane; the carbocation rearranges to a tert-butyl group stabilized by hyperconjugation, a particular form of delocalization.
Delocalized electrons also exist in the structure of metals. Metallic structure consist of aligned positive ions (cations) in a "sea" of delocalized electrons. This means that the electrons are free to move throughout the structure, and gives rise to properties such as conductivity.
In diamond all four outer electrons of each carbon atom are 'localized' between the atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. The delocalized electrons are free to move throughout the plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct in a direction at right angles to the plane.
A conjugated system occurs in an organic compound where atoms covalently bond with alternating single and multiple (e.g. double) bonds (e.g., C=C-C=C-C) and influence each other to produce a region called electron delocalization. In this region electrons do not belong to a single bond or atom, but rather a group. For example, phenol (C6H5OH, benzene with hydroxyl group) (diagramatically has alternating single and double bonds), which has a system of 6 electrons above and below the flat planar ring, as well as around the hydroxyl group.
The conjugated system results in a general delocalization of the electrons across all of the adjacent parallel aligned p-orbitals of the atoms, which increases stability and thereby lowers the overall energy of the molecule [1].
Conjugation can be maintained by the presence of different kinds of p-orbital-donating groups. Furan is considered a conjugated system for this reason.
Conjugation is possible by means other than the presence of alternating single and double bonds. As long as each contiguous atom in a chain possesses a p-orbital, the system can be considered conjugated. For example, furan (shown at right) is a five-membered ring with two alternating double bonds and an oxygen in position 1. Oxygen has two lone pairs, one of which occupies a p-orbital on that position, thereby maintaining the conjugation of that five-membered ring. The presence of a nitrogen in the ring or groups α to the ring like a carbonyl group (C=O), an imine group (C=N), a vinyl group (C=C), or an anion will also suffice as a source of pi orbitals to maintain conjugation.
Conjugated systems have unique properties that give rise to strong colors. Many pigments make use of conjugated electron systems, such as beta-carotene's long conjugated hydrocarbon chain resulting in a strong orange color. When an electron in the system absorbs a photon of light of the right wavelength, it can be promoted to a higher energy level. (See particle in a box). Most of these electronic transitions are of a p-orbital electron to a p-antibonding orbital (π to π*), but non-bonding electrons can also be promoted (n to π*). Conjugated systems of fewer than eight conjugated double bonds absorb only in the ultraviolet region and are colorless to the human eye. With every double bond added, the system absorbs photons of longer wavelength (and lower energy), and the compound ranges from yellow to red in color. Compounds that are blue or green typically do not rely on conjugated double bonds alone.
This absorption of light in the ultraviolet to visible spectrum can be quantified using UV/VIS spectroscopy, and forms the basis for the entire field of photochemistry.
Chemical structure of beta-carotene. The eleven conjugated double bonds that form the chromophore of the molecule are highlighted in red.
Conjugated systems form the basis of chromophores, which are light-absorbing parts of a molecule which can cause a compound to be colored. Such chromophores are often present in various organic compounds and sometimes present in polymers, which are colored or glow in the dark. They are usually caused by conjugated ring systems with bonds such as C=O and N=N in addition to conjugated C-C bonds.
The native conformation of cyclooctatetraene. Adjacent double bonds are not coplanar, so there is not strong conjugation between them.
Conjugation in cyclic structures results in aromaticity, an unusual stability found in cyclic conjugated systems.
It is important to note that merely possessing alternating double and single bonds is not enough for a system to be strongly conjugated. Some cyclic hydrocarbons (such as cyclooctatetraene) do indeed possess alternating single and double bonds. Although the molecule may appear planar if one looks only at its chemical structure, it is in fact not, and typically adopts a "tub" conformation. Because the p-orbitals of the molecule do not align themselves well in this non-planar molecule, the electrons are not as easily shared between the carbon atoms. They can be still considered conjugated, but they are not considered antiaromatic (and also not aromatic; see Hückel's rule). Cyclooctatetraene would not be considered antiaromatic because it is not planar.
Subscribe to:
Posts (Atom)
