Condensed Formula Definition in Chemistry

The condensed formula of a molecule is the formula where the symbols of atoms are listed in order as they appear in the molecule's structure with bond dashes omitted or limited. While vertical bonds are always omitted, sometimes horizontal bonds are included to indicate polyatomic groups. Parentheses in a condensed formula indicate the polyatomic group is attached to the central atom to the right of the parentheses. A true condensed formula can be written on a single line without any branching above or below it.

Condensed Formula Examples

Hexane is a six-carbon hydrocarbon with a molecular formula of C₆H₁₄. The molecular formula lists the number and type of atoms but gives no indication of the bonds between them. The condensed formula is CH₃(CH₂)₄CH₃. Although less commonly used, the condensed formula of hexane could also be written as CH₃CH₂CH₂CH₂CH₂CH₃. It's easier to visualize a molecule from its condensed formula than from its molecular formula, particularly when there are multiple ways the chemical bonds could form.

Two ways to write a condensed formula of propan-2-ol are CH₃CH(OH)CH₃ and (CH₃)CHOH.

More examples of condensed formulas include:

propene: CH₃CH=CH₂

isopropyl methyl ether: (CH₃)₂CHOCH₃