JEE Main & Advanced Physics Atomic Physics Bohr's Atomic Model

Bohr proposed a model for hydrogen atom which is also applicable for some lighter atoms in which a single electron revolves around a stationary nucleus of positive charge Ze (called hydrogen like atom)

Bohr's model is based on the following postulates.

(1) He postulated that an electron in an atom can move around the nucleus in certain circular stable orbits without emitting radiations.

(2) Bohr found that the magnitude of the electron's

Angular momentum is quantized i.e. \[L=m{{v}_{n}}{{r}_{n}}=n\,\left( \frac{h}{2\pi } \right)\]

where n = 1, 2, 3, ..... each value of n corresponds to a permitted value of the orbit radius.

\[{{r}_{n}}=\] Radius of \[{{n}^{th}}\] orbit, \[{{v}_{n}}=\] corresponding speed

(3) The radiation of energy occurs only when an electron jumps from one permitted orbit to another.

When electron jumps from higher energy orbit \[({{E}_{2}})\] to lower energy orbit \[({{E}_{1}})\] then difference of energies of these orbits i.e. \[{{E}_{2}}-{{E}_{1}}\] emits in the form of photon. But if electron goes from \[{{E}_{1}}\] to \[{{E}_{2}}\] it absorbs the same amount of energy.