Atomic Theory

Niels Bohr

So let's get back to the electron. We know that the electron is found somewhere surrounding the nucleus. Rutherford's planetary model was fundamentally flawed due to the laws of physics. The next scientist to offer an insight to the structure of the atom was Niels Bohr. He offered a modification of the planetary model from Rutherford that would solve the problem of the electron colliding with the nucleus. With Rutherford's model, this would cause the full spectrum of light colors to be emitted from an atom as the electron traveled toward the nucleus; however, the atom was stable and each element only showed certain colors of light when their spectra were analyzed (more on this shortly).

He developed a theory that the electrons in the orbits around the nucleus are placed in fixed energy states surrounding the nucleus. The electrons could only occupy these fixed energy states surrounding the nucleus and no where in between. A representation of the Bohr model is shown to the right.

An electron could have an energy associated with the first electron shell or the second electron shell, but could not be found anywhere in between those two energy states. He used the spectrum of hydrogen to validate his atomic model.