What are the postulates of Bohr’s model of an atom?

AcademicChemistryNCERTClass 9

Bohr\'s model of the atom was proposed by Neil Bohr in 1915. The postulates of Bohr’s model of an atom are given below:
  • In an atom, electrons (negatively charged) revolve around the positively charged nucleus in a certain definite path called orbits or shells. Each orbit or shell has fixed energy and these circular orbits are known as orbital shells.
  • The energy levels are represented by an integer (n=1, 2, 3…) known as the quantum number. This range of quantum numbers starts from the nucleus to the side with n=1 having the lowest energy level. The orbits n=1, 2, 3, 4… are assigned as K, L, M, N….. shells and when an electron attains the lowest energy level it is said to be in the ground state.
  • The electrons in an atom move from a lower energy level to a higher energy level by gaining the required energy and an electron moves from a higher energy level to a lower energy level by losing energy. 
  • The electron can move only in that orbit in which angular momentum is quantized, i.e., the angular momentum of the electron is an integral multiple of h/2π.
Updated on 10-Oct-2022 13:32:35