化学式
A way of presenting information about the [[chemistry|chemical]] proportions of atoms that constitute a particular [[chemicals|chemical]] compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, and plus (+) and minus (−) signs. Unlike [[chemical structure]], these are limited to a single typographic line of symbols, which may include subscripts and superscripts. 

For example, H₂O for [[water]] and C₇H₅N₃O₆ or C₆H₂(NO₂)₃CH₃ for [[tnt|trinitrotoluene]].
chemical formula