Introduction to Matter (Book)

Molecules and Crystals

The smallest particle of a compound that still has the compound’s properties is a molecule. A molecule consists of two or more atoms that are joined together. For example, a molecule of water consists of two hydrogen atoms joined to one oxygen atom (see Figure below). You can learn more about molecules at this link: http://www.nyhallsci.org/marvelousmolecules/marveloussub.html.

Some compounds form crystals instead of molecules. A crystal is a rigid, lattice-like framework of many atoms bonded together. Table salt is an example of a compound that forms crystals (see Figure below). Its crystals are made up of many sodium and chloride ions. Ions are electrically charged forms of atoms.