Humans are trichromats, sensitive to three fundamental wavelengths of visible light. Although our color perception is the most advanced amongst mammals, humans have less effective color vision than many birds, reptiles, insects and even fish. Vegetation will not appear to animals as it does to us. The element chlorine derives its name from the same source, being a yellowish-green gas. Chlorophyll occurs in a variety of forms.Ĭhlorophyll does not contain chlorine as the name might suggest the chloro- portion stems from the Greek chloros, which means yellowish green. The porphyrin contains four nitrogen atoms bonded to the magnesium ion in a square planar arrangement. A chelate consists of a central metal ion bonded to a large organic molecule, composed of carbon, hydrogen, and other elements such as oxygen and nitrogen.Ĭhlorophyll has magnesium as its central metal ion, and the large organic molecule to which it bonds is known as a porphyrin. However, there is still a large spectral region between 500 and 600 nm where chlorophyll absorbs very little light, and plants appear green because this light is reflected.Ĭhlorophyll is a compound that is known as a chelate. Plants are able to satisfy their energy requirements by absorbing light from the blue and red parts of the spectrum. The two kinds of chlorophyll in plants complement each other in absorbing sunlight. Light with a wavelength of 460 nm is not significantly absorbed by chlorophyll a, but will instead be captured by chlorophyll b, which absorbs strongly at that wavelength. Absorption spectra showing how the different side chains in chlorophyll a and chlorophyll b result in slightly different absorptions of visible light.

Absorption spectra of chlorophyll