Answer to Question #49207 in Physics for Trevor

The emission spectrum of all elements consistsof discrete wavelengths. Electrons only exist in particular orbitals. They do
not spin willy-nilly around the nucleus. If they receive energy, they jump from
one orbital to a higher orbital. When they fall back to a lower orbital, they
give off a discrete amount of energy. That discrete amount of energy comes as
the form of light of a particular wavelength. Look at it as an electron having
to be on one or another step instead of a ramp. Instead of continually rolling,
it goes one step at a time.