Riot control agent. After September 11, 2001, the _____________ was established to provide a framework that provides a comprehensive national approach, applicable at all jurisdictional levels and across functional disciplines.
noun, plural: chemicals. (1) A substance made up of chemical elements or produced from a chemical process. (2) A drug, especially illicit or addictive drug. adjective. Of, relating to, or pertaining to, chemistry or a chemical substance.
Element Definition: A chemical element is a substance that cannot be broken down by chemical means.Elements are defined by the number of protons they possess. Examples of Elements: copper, cesium, iron, neon. By Anne Marie Helmenstine, Ph.D.lement Definition: A chemical element is a substance that cannot be broken down by chemical means.