Question

1) Describe Bohr’s quantum model of the atom.

2) Derive expressions for the energies and radii of an electron in the hydrogen atom.

3) Discuss experiments that confirmed the existence of quantized atomic energy levels.

Answer 1

(1)

Bohr's quantum model of the atom :

According to the Bohr's quantum model , an atom consists of a positively charged nucleus which is surrounded by electrons ( negatively chrged particles) .

A small positively charged nucleus is surrounded by revolving negatively charged electrons in fixed orbits. Electrons will have more energy if it is located away from thr nucleus whereas the electrons will have less energy if it is located near the nucleus.

Postulates of Bohr's atomic model :

• Electrons revolve around nucleus in a fixed circular orbit or energy levels.
• Every circular orbit have a certain amount of fixed energy. The electrons will not rediate energy as long as they revolve around the nucleus in fixed orbit .
• The different energy levels are denoted by integers such as n=1 , n=2 , n=3 and so on . These are known as quantum numbers .
• The change in energy occurs when electrons jump from one energy level to other.
• In an atom the electrons move from lower to higher energy level by acquiring the required energy. And electron loses energy when it moves from higher energy level to lower energy level.