How it works
This naming of alkanes worksheet has 37 IUPAC questions: straight chains from methane to decane, branched alkanes from condensed formulas and back, wrong names to correct, and alkenes, alkynes and isomers.
Read the full guide
Four sets
Straight chains covers the ten chain names and CₙH₂ₙ₊₂. Branched alkanes names condensed formulas and matches names to them. Fix the wrong name shows the usual mistakes. The last set adds -ene, -yne, rings and isomers.
Print or practise
Practice brings a missed question back until you get it right. The sheet on screen is what prints: remove a question, add more up to all 37, and tick With answer key.
- Find the longest chain first, even if it bends through a branch written in brackets.
- Number from the end nearer the first branch, so the numbers are as low as possible.
- List different branches alphabetically; use di- and tri- for repeats, with every number.
Questions and answers
What are the steps for naming an alkane?
Find the longest carbon chain and name it (pentane, hexane). Number it from the end nearer a branch. Name each branch with its number, in alphabetical order, with di- or tri- for repeats: 3-ethyl-2-methylhexane.
What are the first ten alkanes?
Methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane and decane, with 1 to 10 carbons. Each has the formula CₙH₂ₙ₊₂, so hexane, with six carbons, is C₆H₁₄.
Why is CH₃CH(CH₂CH₃)CH₂CH₃ not 2-ethylbutane?
The ethyl group is part of the longest chain. Counting through it gives five carbons with a methyl on carbon 3, so the name is 3-methylpentane.