Any of numerous chemical compounds related to phosphoric acid (HPO). Phosphate salts are inorganic compounds containing the phosphate ion (PO3), the hydrogen phosphate ion (HPO2), or the dihydrogen phosphate ion (HPO), along with any cation. Phosphate esters are organic compounds in which the hydrogens of phosphoric acid are replaced by organic groups (e.g., methyl, ethyl, phenyl), with one of their carbon atoms bonding to an oxygen atom in the phosphate group. Nucleic acids and ATP both contain phosphate; bones and teeth contain calcium phosphate. Phosphate rock (mainly calcium phosphate) is one of the four most important basic chemical commodities. Phosphates were formerly used in detergents, which washed into rivers and lakes, causing water blooms of algae and bacteria (see eutrophication); such use is now generally outlawed or regulated. Phosphates are still used in fertilizers, baking powder, and toothpaste.

This entry comes from Encyclopædia Britannica Concise.
For the full entry on phosphate, visit

Seen & Heard

What made you look up phosphate? Please tell us what you were reading, watching or discussing that led you here.