Bohr's Atomic Model And Its Limitations

Aug 26, 2022, 16:45 IST

Atomic Structure

Development of structure of Atom and historical Models; Spectrum of hydrogen atom; Bohr model; de Broglie relation, Uncertainty principle, Quantum model; Electronic configuration of elements (upto to atomic number 36); Aufbau principle, Pauli’s exclusion principle and Hund’s rule; shapes of s, p, and d orbitals; Probability Density Curves (Radial and Angular).

D A L T O N ’ S Atomic Theory And Thomson’s Cathode Ray Experiment

1. John Dalton (1801), believed that matter is made up of extremely minute indivisible particles, called atoms.

2. J.J. Thomson (1897), produced cathode rays by passing electric discharge through gas at low pressure. The properties of cathode rays are:

(a) They travel in a straight line with high velocity and cast shadow.

(b) They produce fluorescence when strike the glass walls of discharge tube, coated with ZnS

(c) They are deflected from straight path by electric and magnetic field which shows that they consist of minute particles electron carrying – ve charge.

ANODE RAY EXPERIMENT

From the analysis of anode rays or positive rays; also produced during the production of cathode rays; it is possible to show that the lightest positive particle in the atom is proton.

NEIL’S BOHR ATOMIC THEORY (1913)

Bohr’s theory is applied to one electronic species. Path of electron is circular and angular momentum of electron is quantised. Bohr’s has given the concept of stationary orbits i.e. while revolving in any orbit, total energy of electron remains constant.