Molecular Formula - Definition - Law Dictionary Home Dictionary Definition molecular-formula

Definition :

An expression representing the composition of elements in a chemical substance commonly consisting of a series of letters and numbers comprising the atomic symbols of each element present in a compound followed by the number of atoms of that element present in one molecule of the substance Thus the molecular formula for common alcohol ethyl alcohol is C2H6O meaning that each molecule contains two carbon atoms six hydrogen atoms and one oxygen atom The molecular formula may be written to provide some indication of the actual structure of the molecule in which case structural units may be written separately Thus ethyl alcohol can also be written as CH3CH2OH or CH3 CH2 OH in which the period or dash between functional groups indicates a single bond between the principle atoms of each group This formula shows that in ethyl alcohol the carbon of a methyl group CH3 is attached to the carbon of a methylene group CH2 which is attached to the oxygen of a hydroxyl group OH A structural formula is a graphical depiction of the relative positions of atoms in a molecule and may be very complicated