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Elements, compounds and mixtures - (CCEA) Types of substances

Most elements are rarely found in their pure form. They are found chemically combined with other elements in compounds. Compounds are often found mixed with other compounds. Mixtures may be separated and analysed.

Part of Combined ScienceElements, compounds and mixtures

Types of substances

Pure substances

'Pure' has a specific meaning in chemistry.

A substance is a single element or compound not mixed with any other substance.

A contains two or more different substances mixed together, usually easy to separate.

Pure substancesMixtures
Diamond only contains the element carbon.Air is a mixture of oxygen, carbon dioxide, nitrogen and other trace gases.
Water only contains the compound water.Mineral water is a mixture of water and dissolved salts.
Table salt only contains the compound sodium chloride.Milk is a mixture of water, lactose, fat and minerals such as salt.
Pure substancesDiamond only contains the element carbon.
MixturesAir is a mixture of oxygen, carbon dioxide, nitrogen and other trace gases.
Pure substancesWater only contains the compound water.
MixturesMineral water is a mixture of water and dissolved salts.
Pure substancesTable salt only contains the compound sodium chloride.
MixturesMilk is a mixture of water, lactose, fat and minerals such as salt.

Here are some examples of pure substances and mixtures.

Chemical substance table