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
AI overview
A chemical substance is a specific type of matter with a fixed composition made up of particular molecules, atoms, or other building blocks, and it has consistent physical properties like density that help identify it. Understanding chemical substances matters because it allows us to identify, classify, and predict how different materials will behave in the world around us.
AI-generated from the Wikipedia summary — may contain errors.
Article
Steam and liquid water are two different forms of the same pure chemical substance, water. Picture of a formed molecule In chemistry, a substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combined without reacting, they may form a chemical mixture. If a mixture is separated to isolate one chemical substance to a desired degree, the resulting substance is said to be chemically pure.
Chemical substances can exist in several different physical states or phases (e.g. solids, liquids, gases, or plasma) without changing their chemical composition. Substances transition between these phases of matter in response to changes in temperature or pressure. Some chemical substances can be combined or converted into new substances by means of chemical reactions. Chemicals that do not possess this ability are said to be inert.