Themes > Science > Chemistry > General Chemistry > Atomic Structure > Electronic Structures of Atoms > Atomic Structure Index > Atomic spectra

If you look at light from an ordinary incandescent bulb through a prism, you will discover that white light is composed of all the various colors. These correspond to different wavelengths of light: the visible range has wavelengths between 400 (blue) nm and 700 nm (red).

If you look at light from excited gas phase atoms of an element, however, you don't see all colors. Rather, you see a series of distinct lines at certain wavelengths which depend on the element. This is why sodium vapor streetlamps look yellow: the two primary wavelengths gaseous sodium emits at are both in the yellow region of the spectrum.

Since photons of a given wavelength have a specific energy

E = hc/l
this implies that there must be something going on in the atom that generates energy of specific frequencies. The Bohr model and the Schrodinger quantum mechanics model are two theories which attempt to explain why atoms give off specific energies of photons.


Information provided by: http://learn.chem.vt.edu