Appendix 1: Units of Measure Used in the Lead-Based Paint Field

An atom is one of the smallest units of matter, identifying a specific element. Lead is an element and is composed of atoms of lead; each lead atom behaves the same way when it interacts with other atoms. A molecule is a cluster of bound atoms which behave as a unit when interacting with atoms or other molecules. Materials made up of molecules are called compounds. The chemical and physical properties of compounds are unlike those of the elements which are present in them. Lead oxide, lead chromate, and lead acetate are all molecules formed when lead atoms combine with atoms of other elements to form molecules. These molecules are called lead compounds or sometimes lead salts. Lead acetate is a lead compound which has a sweet taste and is called "sugar of lead."