When combined with other elements, metals form compounds named generally after the element with which they are united. Thus, compounds with chlorine are called chlorides; with bromine, bromides; and iodine, iodides.

- The most common compounds of metals arc given in the following table.

Compounds With

Oxygen form oxides.

Oxygen and hydrogen form hydroxides.

Sulphur form sulphides.

Sulphur and hydrogen form hydrosulphides.

Nitric acid form nitrates.

Nitrous acid form nitrites.

Acids of chlorine and oxygen form chlorates.

Sulphuric acid form sulphates.

Sulphurous acid form sulphites.

Carbonic acid form carbonates. Phosphoric acid form phosphates. Arsenical acid form arsenates. Silicic acid form silicates. Boric acid form borates.

Many of the compounds are found in nature; thus sulphate of calcium (CaSO4) is a very common salt called gypsum; oxide of iron, made up of iron and oxygen, is called iron ore; and carbonate of iron (FeCO3) is another form of iron ore.