Bohr Atom Model

The Bohr Model has atom comprising of the small, positively-charged nucleus orbited by negatively-charged electrons. It is the model of the atom which explains emission and absorption of radiation as transitions among stationary electronic states in which the electron orbits the nucleus at a definite distance. The electrons orbit the nucleus in orbits that have a fixed size and energy. The energy of the orbit is related to the size of it. The lowest energy is found in smallest orbit. Radiation is emitted or absorbed when an electron moves from one orbit to another.

The Bohr's model of the atom described electrons as orbiting in discrete, precisely defined circular orbits. These circular orbits are called as energy levels. Electrons can occupy certain allowed orbitals only. For an electron to occupy the allowed orbit, some amount of energy should be available. Each orbit is assigned a quantum number, with lowest quantum numbers being assigned to those orbitals closest to the nucleus. A pre specified maximum number of electrons can occupy the orbital. Energy of the electron is constant in one of the allowed orbits of it. As long as an electron remains in its orbit, it does not absorb nor radiates energy. If an electron jumps from higher energy level to the lower energy level, it radiates a definite amount of   energy. Energy absorbed or released by an electron is equal to the difference of energy of two energy levels.

Bohr's model has certain limitations such as: it violates the Heisenberg Uncertainty Principle as it considers electrons to have a known radius and orbit both; the Bohr Model provides incorrect value for the ground state orbital angular momentum; it makes bad predictions regarding the spectra of larger atoms; it doesn't predict the relative intensities of spectral lines; the Bohr Model does not explain the fine structure and hyperfine structure in the spectral lines; and it does not explain Zeeman Effect.