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Chemical substance

A chemical substance is any material substance used in or obtained by a process in chemistry. It can be an element, a compound, or a mixture thereof:

• A chemical element is a substance that cannot be divided or changed into different substances by ordinary chemical methods. The smallest particle of such an element is an atom, which consists of electrons centered about an nucleus of protons and neutrons.

• A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions.

• A molecule is the smallest particle of an element or compound that retains the chemical characteristics of the element or compound.

• An ion is an atom or group of atoms with a net electric charge, having lost (cation) or gained (anion) an electron.

• The term “chemical” may refer to any chemical substance, though a popular meaning is “a product of the chemical industry”. As such the term may carry connotations of being “unnatural” and perhaps harmful, even when such fears are unjustified, as with the dihydrogen monoxide hoax.