Carbonate, << KAHR buh nayt, >> is any compound that contains the carbonate ion. An ion is an atom or a group of atoms with an electric charge. The carbonate ion has two negative charges and consists of one carbon atom and three oxygen atoms. Chalk, marble, and other limestones are examples of a naturally abundant carbonate, calcium carbonate. Animal bones and teeth as well as egg and oyster shells have large amounts of calcium carbonate.
Carbonate ions combined with metal ions form the most common carbonates, including calcium carbonate. These metal carbonates can be produced by allowing a water solution of a chemical base, such as sodium hydroxide, to combine with carbon dioxide. The reaction produces a bicarbonate (carbonate that includes a hydrogen ion). A carbonate compound results from heating a bicarbonate compound. For example, common washing soda (sodium carbonate) results from heating baking soda (sodium bicarbonate).
