what is substance called when it has two elements
By Anne Marie Helmenstine, Ph.D. A compound is a chemical substance made up of two or more elements. Here is a list of examples of compounds made up of exactly two elements. 1  H 2 O-water. 2  NaCl-sodium chloride or table salt. 3  KCl-potassium chloride. 4  HCl-hydrochloric acid. 5  N 2 O-nitrous oxide. 6  AgI-silver iodide. 7  AlN-aluminum nitride.