1913 Bohr's Atom

Bohr (1885-1962) Bohr's student, Otto Frisch said," He moved with the skill of a spider in apparently empty space, judging accurately how much weight each slender thread of argument could bear."

In 1913, Bohr made two suggestions to improve Rutherford's atomic model:

• Electrons can revolve round the nucleus only in certain allowed orbits and they do not emit radiation when they are in these orbits. Each orbit is associated with a certain quantity of energy.

• An electron can "jump" from one orbit to another orbit absorbing or releasing energy. When it moves inwards, energy is emitted as radiations. If it moves outwards, energy is absorbed.

However, the Bohr atom involved quantities like the radius of an orbit which could not be measured experimentally. Therefore, Bohr's model of the atom was later superseded by a new theory based on wave mechanics. Nevertheless, the essential characteristic of Bohr's orbits, i.e. definite energy values, retained.

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