Bohr’s theory to hydrogen-like atoms and ions; spectrum of hydrogen atom. Quantum numbers. Introduction to the concept of atomic orbitals; shapes, radial and angular probability diagrams of s, p and d orbitals (qualitative idea). Many electron atoms and ions: Pauli’s exclusion principle, Hund’s rule, exchange energy, Aufbau principle and its limitation. Electronic energy level diagram and electronic configurations of hydrogen-like and polyelectronic atoms and ions up to atomic number 30.

Periodic table, group trends and periodic trends in physical properties.Classification of elements on the basis of electronic configuration. Modern IUPAC Periodic table. General characteristic of s, p, d and f block elements. Position of hydrogen and noble gases in the periodic table. Effective nuclear charges, screening effects, Slater’s rules, atomic radii, ionic radii (Pauling’s univalent), covalent radii. Ionization potential, electron affinity and electronegativity (Pauling, Mulliken and Allred-Rochow scales) and factors influencing these properties. Inert pair effect. 

Size effects, radius ratio rules and their limitations. Packing of ions in crystals, ionic compounds of the type AX (ZnS, NaCl, CsCl) and AX₂ (CaF2-fluorite) lattice energy, Born–Landéequation and its applications, Born-Haber cycle and its applications. Solvation energy, polarizing power and polarizability, ionic potential,Fajans’ rules. Defects in solids.

Lewis structures, formal charge. Valence Bond Theory, directional character of covalent bonds, hybridizations, equivalent and non-equivalent hybrid orbitals, Bent’s rule, VSEPR theory, shapes of molecules and ions containing lone pairs and bond pairs (examples from main groups chemistry), partial ionic character of covalent bonds, bond moment, dipole moment and electronegativity differences. Concept of resonance, resonance energy, resonance structures.