The main postulates of Neil’s Bohr are as follows.
1. In atoms, electrons revolve around the nucleus in special orbits called discrete orbits or shells or energy levels.
2. While the electrons revolve, they do not radiate energy.
3. The circular orbits are numbered as 1,2,3,4 or designated as K, L, M, N shells. These numbers are referred as principal quantum numbers (n).
4. K shell (n = 1) is closer to the nucleus and is associated with lowest energy. L, M, N are the next higher energy levels. As the distance from the nucleus increases, the energy of the shells also increase.
5. The energy of each orbit or shell is a fixed quantity.
6. As the distance from the nucleus increases, the size of the orbits also increases.
7. The maximum number of electrons that can be accommodated in an energy level is 2n (n = quantum number of its orbit).
8. When an electron absorbs energy, it jumps from lower energy level to higher energy level.
9. When an electron returns from higher energy level to lower energy level, it gives off energy.
