| A | B |
|---|
| binary compound | a compound that contains only two elements |
| formula unit | the simplest ratio of ions in a compound |
| oxidation number | the charge on an ion |
| polyatomic ion | an ion that has two or more different elements |
| hydrate | a compound in which there is a specific ratio of water to ionic compound |
| hygroscopic | ionic compounds that can easily become hydrates by absorbing water molecules from water vapor in the air |
| deliquescent | substances that are so hygroscopic that they take up enough water from the air to dissolve completely and form a liquid solution |
| anhydrous | a compound in which all of the water has been removed |
