Elements and Compounds Elements, Atoms, and Molecules Elements are substances that cannot be separated into simpler substances.
Salt is made up of the elements sodium and chloride.
Water is made up of the elements hydrogen and oxygen. The smallest particles of matter are called atoms . Remember the carrot from the other chapter. If you continue to chop a carrot into smaller and smaller pieces, eventually you would reach a point where you could not cut up the carrot anymore, but still have carrot. You would then have molecules of carrot.