Postulates of Bohr’s Model of an Atom
1. In an atom, electrons revolve around the positively charged nucleus in definite orbits. Each orbit has fixed energy.
2. The energy levels of an atom are represented by an integer (n=1, 2, 3…) . The orbits n=1, 2, 3, 4… are represented as K, L, M, N…. shells.
3. 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 lower energy level by losing energy.
Limitations of Rutherford model of atom
1. Rutherford’s model was unable to explain the stability of an atom.
2. It did not explain the arrangement of an electron in orbit.
3. Electrons revolve around the nucleus in a circular path. But if particles are in motion on a circular path, they would undergo acceleration, which causes radiation of energy by charged particles. Eventually, electrons should lose energy and fall into the nucleus. Rutherford was not able to explain this.