11th Class Chapter No 2 - Atomic Structure in Chemistry for ISC

Structure of Atom
Discovery of fundamental particles electron, proton and neutron), atomic number, isotopes and isobars. Thomson's model and its limitations. Rutherford's experimental model and its limitations. Dual nature of matter and light. Bohr's atomic model and its limitations (de Broglie's equation, Heisenberg’s uncertainty principle), concept of shells, subshells, orbitals. Quantum numbers, shapes of s, p and d orbitals. Rules for filling electrons in orbitals - aufbau principle, Pauli's exclusion principle and Hund's rule of maximum multiplicity. Electronic configuration of atoms, stability of half-filled and completely filled orbitals.

1. Subatomic particles (electrons, protons and neutrons) their charges and masses: Concept of indivisibility of atom as proposed by Dalton does not exist. The atom consists of subatomic fundamental particles. Production of cathode rays and their properties. Production of anode rays and their properties.
   Chadwick’s experiment for the discovery of neutron and properties of neutron.
2. Rutherford’s nuclear model based on the scattering experiment: Rutherford’s scattering experiment. Discovery of nucleus. Rutherford’s nuclear model of atom. Defects of Rutherford’s model. Electromagnetic wave theory and its limitations (Black body radiation and photoelectric effect)
   Planck’s quantum theory.
   Numericals based on the above.
3. Types of spectra: emission and absorption spectra. Band and line spectra to be discussed.
4. Bohr’s atomic model.
   Postulates of Bohr’s theory – based on Planck’s quantum theory.
   Merits of Bohr’s atomic model and explanation of hydrogen spectra.
   Calculations based on Rydberg’s formula.
   Numericals on Bohr’s atomic radii, velocity and energy of orbits (derivation not required).
   Defects in Bohr’s Model.
5. Quantum mechanical model of an atom - a simple mathematical treatment. Quantum numbers; shape, size and orientation of s, p and d orbitals only (no derivation). aufbau principle, Pauli’s exclusion principle, Hund’s rule of maximum multiplicity. Electronic configuration of elements in terms of s, p, d, f subshells.
   • de Broglie’s equation. Numericals.
   • Heisenberg’s Uncertainty Principle. Numericals.
   • Schrodinger Wave Equation – physical significance of ψψ and |ψ|2|ψ|2.
   • Quantum numbers – types of quantum numbers, shape, size and orientation of the s, p and d subshells. Information obtained in terms of distance of electron from the nucleus, node, nodal planes and radial probability curve, energy of electron, number of electrons present in an orbit and an orbital.
   • aufbau principle, (n+l) rule.
   • Pauli’s exclusion principle.
   • Hund’s rule of maximum multiplicity.
   • Electronic configuration of elements and ions in terms of s, p, d, f subshells and stability of half-filled and completely filled orbitals.