Explain the postulates of Bohr’s atomic model.

The main postulates of Bohr’s atomic model are:

● In atoms, electrons revolve around the nucleus in certain special or permissible orbits known as orbits or shells or energy levels.

● While revolving in these orbits the electrons do not radiate energy.

● The circular orbits are numbered as 1, 2, 3, 4, … or named as K, L, M, N, shells. These numbers are referred to as principal quantum numbers (n).

● K shell (n = 1) is closest to the nucleus and is associated with lowest energy. L, M, N, …. etc are the next higher energy levels. As the distance from the nucleus increases the energy of the shells also increases.

● The energy of each orbit or shell is a fixed quantity and the energy is quantized.

● As the distance from the nucleus increases, the size of the orbits also increases.

● Maximum number of electrons that can be accommodated in an energy level is given by 2n² where n is the principal quantum number of the orbit.

● When an electron absorbs energy, it jumps from lower energy level to higher energy level.

● When an electron returns from higher energy level to lower energy level, it gives off energy.