Atomic number is represented by:

Number of protons present inside the nucleus

Number of neutrons present inside the nucleus

Number of proton and neutron present inside the nucleus

Write postulates of Bohr's atom model.

Postulates of Bohr’s atomic model are: 1. In an atom, the electrons revolve around the nucleus in certain definite circular paths called orbits, or shells named as K, L, M etc. 2. Each shell or orbit corresponds to a definite energy. Therefore, these circular orbits are also known as energy levels or energy shells. 3. The energy of an orbit is quantized. Since, electrons can be present only in these orbits, hence, these electrons can only have energies corresponding to these energy levels, i.e., electrons in an atom can have only certain permissible energies. 4. The angular momentum of the electron is an integral multiple of h / 2 π . 5. The electrons present in an atom can move from a lower energy level to a level of higher energy by absorbing the appropriate energy. Similarly, an electron can jump from a higher energy level to a lower energy level by losing the appropriate energy.