Chemical substance

matter of constant composition best characterized by the entities (molecules, formula units, atoms) it is composed of and characterized by physical properties like density / From Wikipedia, the free encyclopedia

A chemical substance is any material with a known chemical composition.[1] For example, water has the same properties and the same ratio of hydrogen to oxygen whether it came from a river or was made in a laboratory. Typical chemical substances found in the home include water, salt (sodium chloride) and bleach. Generally, substances exist as a solid, a liquid, or a gas, and may change between these phases of matter when there are changes in temperature or pressure.

Water and steam are two different forms of the same chemical substance

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