Step 1: find the parent chain
Identify the longest continuous carbon chain. It doesn't have to be drawn in a straight line — it just has to be connected. If two chains tie for length, pick the one with the most substituents. The number of carbons gives the parent name: methane (1), ethane (2), propane (3), butane (4), pentane (5), hexane (6), heptane (7), octane (8), nonane (9), decane (10).
Step 2: number to give low locants
Number the parent chain from the end that gives the lowest set of locants for the substituents. "Lowest set" means compare locants at the first point of difference — {2,3,5} beats {3,4,5} because 2 < 3. If both ends give identical sets, use alphabetical priority of substituents to break the tie.
Step 3: name the substituents
Branch names use the same prefixes as parent chains but end in -yl: methyl (CH₃), ethyl (C₂H₅), propyl, butyl, etc. Multiple identical branches get di-, tri-, tetra- prefixes. Each substituent gets a locant number telling you where on the parent chain it's attached.
Step 4 & 5: assemble
List substituents alphabetically (ignoring di-/tri- prefixes for sorting, but keeping them in the final name). Separate locants with commas, separate locants from names with hyphens. Example: 3-ethyl-2,4-dimethylhexane. "Ethyl" comes before "methyl" alphabetically; di- prefix doesn't count for sorting.
Draw this on the whiteboard
Open the OChem Board whiteboard — benzene rings, wedge/dash bonds, and a clickable periodic table built in. No account needed.