Atom Bohr Model:

In 1913, Bohr suggested a model of the atom for which he was awarded Nobel Prize for Physics in 1922. He suggested that the electrons are negatively charged particles and move round the nucleus in various orbits. The orbit of an electron is fixed. He gave the name Energy Levels to these orbits. The electron cannot emit any energy when it moves in its own fixed orbit known as stationary energy level. In fig. the dotted line orbit is ruled out in Bohr's model and only thick line orbits are present. It means that the orbits of definite radii are present but orbits of all radii are ruled out. The electrons gives out energy in the form of electromagnetic radiations of definite frequency when it jumps from higher energy level to lower energy level. The Bohr model opened the way to new concepts in the twentieth century.