Chemical Formula
A symbolic notation that states which elements a substance contains and in what proportions, using element symbols and subscripts.
Unit
Dimensionless
In depth
Subscripts give atom counts within one unit, prefixed coefficients give the number of units, and charges are written as superscripts. Different formula types — empirical, molecular, structural, condensed and skeletal — encode increasing amounts of information about connectivity and geometry.
Examples in the real world
H₂O, Ca(OH)₂, SO₄²⁻, and CH₃CH₂OH, which shows ethanol's connectivity as well as its composition.