Electromagnetic energy is energy that travel trough the space in regularly spaced waves, much as water travels across the ocean in waves.

The Electromagnetic Spectrum

In electromagnetic radiation, the longer the wavelength, the lower the energy level. Radio waves have the lowest energy on the spectrum, gamma rays , the highest.

In the electromagnetic spectrum, each wavelength corresponds to a specific level of energy; longer wavelengths correspond to lower energy levels, whereas shorter wavelength correspond to higher energy levels (see the electromagnetic spectrum);

1. Radiowaves followed by microwaves have the longest wavelength and the lowest energy levels, radiowaves include wavelength used for television, microwaves for cooking.
2. Infrared Light, the next component of the electromagnetic spectrum, is an invisible light that produces heat. Its aids i the identification of substances or compounds from their molecular structure and has special applications in chemistry and health care.
3. Visible light, most commonly observed as white light, is actually composes of the whole spectrum of colors that appear in a rainbow.
4. Ultraviolet radiation or light has shorter wavelength and therefore higher energy than visible light.
5. X-rays and gamma rays have the shorter wavelengths and greatest energy levels; both have significant medical application.

Full review at: Inorganic Chemistry by Mary Jean Rutherford, Med. MT (ASCP)SC