Question

Write the postulates of Bohr's atom model.

Answer 1

Bohr's model:

• In $1915$ Neils Bohr proposed an atom model by slightly modifying Rutherford's atomic model. Rutherford's atomic model suggests that a positive charge nucleus is surrounded by electrons which are having a negative charge.

Postulates of Bohr's atomic model:

• Bohr proposed that in an atom electron is revolving around the nucleus in a definite circular path called orbits or shells.
• These orbits are called ‘stationary orbits’ and each orbit or shell possesses fixed energy.
• The energy levels are represented by an integer called quantum numbers where $\mathrm{n}=1,2,3,....$. These integers $\mathrm{n}=1,2,3,....$indicate principal quantum numbers i.e. orbits that can be assigned as $\mathrm{K},\mathrm{L},\mathrm{M}\&\mathrm{N}$. Thus, the electron in the lower energy state is called the ground state.
• The change in energy will occur when the electron jumps from one orbit to another orbit.
• The electron gains energy when it jumps from a lower energy level to a higher energy level and the electron loses its energy as it jumps from the higher energy to a lower energy level.
• The electron's angular momentum is quantized in its orbitals. So, electrons can move only those permissible orbits that should be an integral multiple of $\frac{\mathrm{h}}{2\mathrm{\pi }}$ where $\mathrm{h}$ is the Planck's constant.