A chemical symbol is the shortform of the name of an element. Usually, it is made up of one or two letters, but sometimes it is made up of three letters. For example, the chemcial symbol for oxygen is O. The chemical symbol for calcium is Ca. Until it is discovered and scientists decide what it will be called, the chemical symbol for ununennium will be Uue.
The chemical symbols are listed with the elements in the periodic table. Chemical symbols are also used when writing chemical formulas. For example, the chemical formula for water is H2O, meaning that it contains two hydrogen atoms and one oxygen atom.