Nomenclature

Organic compounds are named using the IUPAC system of nomenclature, so that every compound has one name that chemists everywhere understand.The stem of the name shows the number of carbon atoms in the longest chain: meth (1), eth (2), prop (3), but (4), pent (5), hex (6), hept (7), oct (8), non (9) and dec (10).A suffix shows the main functional group or homologous series, for example -ane for alkanes, -ene for alkenes, -ol for alcohols and -oic acid for carboxylic acids.Prefixes show side chains and some groups, such as methyl-, ethyl-, chloro- and bromo-. Numbers (locants) show where groups are on the chain. The chain is numbered from the end that gives the lowest numbers.For example, CH₃CH(OH)CH₃ is propan-2-ol: three carbons (prop), an alkane chain (an), an OH group (ol) on carbon 2.