Condensed formula

A condensed formula is a deliberate simplification of the full structural formula: rather than drawing out every single covalent-bond dash, some or all of the bonds are simply hidden, and wherever an atom carries several identical attached groups, that repetition is written as a subscript instead of being spelled out group by group. Ethane, for example, whose full structural formula shows two carbons joined to each other and each carrying three separate C-H dashes, can be condensed to CH3-CH3 (keeping just the central C-C bond dash visible, with each terminal carbon's three hydrogens folded into a 'CH3' subscript group) or condensed even further to CH3CH3 (dropping the central dash too, since the two CH3 groups being adjacent already implies they are bonded). This kind of formula trades a little explicit bonding detail for a large gain in …