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


Light travels through space as a wave. In addition, quantum mechanics tells us that particles also act like waves, so understanding some basic terminology about waves is useful.

The most important characteristics of a wave are its wavelength, frequency, and amplitude. A picture of a wave is shown below with the wavelength and amplitude marked:

Wave diagram

The wavelength (l) of a wave is the distance between two successive peaks of the wave. The frequency (n) of a wave is the number of cycles that pass the observer in a given time. It is related to the wavelength by the simple relationship

n = s/l
where s is the velocity of the wave. For light waves, the velocity s is equal to the speed of light, c, (2.998*108 m/s) so for light waves this relationship is
n = c/l
The amplitude of a wave is the distance between the peak of a wave and the midpoint of the wave. Neither the wavelength or frequency of a wave depend on the amplitude.

The color of light depends on its wavelength. Visible light has wavelengths from ~400-700 nanometers long. The 400 nm light (higher energy) is blue, the 700 nm light is red, and the various colors fall in between the two.

Example: What is the wavelength of a light wave with frequency 1.35*107 1/s?

Solution: Simply use the relationship between the frequency and wavelength of a light wave

n = c/l
Solving this for the wavelength gives
l = c/n
so we have
l = 2.998*108 m/s /1.35*107 1/s
l = 0.0222 meters


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