The Bohr model of the atom was proposed by Neil Bohr in 1915. It came into existence with the modification of Rutherford’s model of an atom. Rutherford’s model introduced the nuclear model of an atom, in which he explained that a nucleus which is positively charged is surrounded by negatively charged electrons.
Postulates of Bohr’s model of the atom
According to Bohr’s theory:
- The atom consists of a small positively charged nucleus at its centre and surrounded by negatively charged electrons in a definite circular path.
- The nucleus contains all the protons and neutrons of the atom.
- The electrons of the atom revolve around the nucleus in definite circular paths known as orbits which are designated as K, L, M, N or numbered as n=1,2,3,4 outward from the nucleus. The orbits are also known as stationary orbits.
- Each orbit is associated with a fixed amount of energy. The lowest energy level of the electron is called the ground state. Therefore, these orbits are also known as energy levels or energy shells.