Compound

During a chemical reaction, atoms from different elements can be rearranged and chemically joined to produce a compound. The product is a new substance, so its properties can be very different from those of the elements from which it formed.

A compound contains atoms of two or more different elements chemically bonded in fixed proportions. Its systematic name is not just a label: the ending of the name can give information about which elements or ions it contains.

A pure compound can contain more than one element. For example, water contains hydrogen and oxygen atoms chemically bonded together, but a sample containing water and no other substance is still pure.

A simple covalent compound consists of non-metal atoms joined by shared electrons. Its molecular formula gives the actual number of atoms of each element in one molecule.