Practice IUPAC nomenclature for alkanes with this free printable chemistry worksheet.
Try these IUPAC naming questions online before (or after) you print the worksheet. Click an answer to check it, or open "Show answer" for the explanation. Each corner and line end in a structure is a carbon atom.
What is the IUPAC name of this alkane?
Answer: 2-methylhexane. The longest chain has 6 carbons (hexane). Numbering from the end closest to the branch puts the methyl group on carbon 2, not carbon 5.
What is the IUPAC name of this alkane?
Answer: 3,3-dimethylpentane. The longest chain has 5 carbons. Two methyl groups sit on carbon 3, so the name needs "di" and a number for each group: 3,3-dimethylpentane.
What is the IUPAC name of this alkane?
Answer: 3-ethyl-2-methylhexane. The longest chain has 6 carbons. Numbering from the left gives locants 2 and 3 (lower than 4 and 5). Substituents go in alphabetical order: ethyl before methyl.
What is the IUPAC name of this alkane?
Answer: 2,3,3-trimethylpentane. The longest chain has 5 carbons with three methyl groups. Numbering from the left gives 2,3,3. From the right it would be 3,3,4. At the first point of difference, 2 is lower than 3.
How many carbon atoms are in the parent chain of an alkane whose name ends in "octane"?
Answer: 8. Oct- means 8, as in octagon. The parent names from 1 to 10 carbons are meth-, eth-, prop-, but-, pent-, hex-, hept-, oct-, non- and dec-.
What is the first step in naming a branched alkane?
Answer: Find the longest continuous carbon chain. Always find the longest continuous chain first. It gives the parent name, and it doesn't have to be drawn in a straight line.
Why is "ethyl" written before "methyl" in 3-ethyl-2-methylhexane?
Answer: Substituents are listed in alphabetical order. Substituent names are listed alphabetically (e before m), no matter their size or position number.
Which prefix shows that there are three identical substituent groups?
Answer: tri-. Di- means 2, tri- means 3 and tetra- means 4. Prefixes like di- and tri- are ignored when putting substituents in alphabetical order.
Each name below breaks an IUPAC rule. Work out the correct name, then check your answer.
What is the correct IUPAC name for 3-methylbutane?
Correct name: 2-methylbutane. The chain was numbered from the wrong end. Count from the end closest to the branch.
What is the correct IUPAC name for 2-propylpentane?
Correct name: 4-methylheptane. The propyl group is part of a longer chain. The longest chain has 7 carbons, with a methyl group on carbon 4.
What is the correct IUPAC name for 1,2-dimethylpropane?
Correct name: 2-methylbutane. A methyl group on carbon 1 just extends the chain. The longest chain is 4 carbons with one methyl group on carbon 2.
What is the correct IUPAC name for 2,2-methylbutane?
Correct name: 2,2-dimethylbutane. Two identical groups need the prefix "di".
Want more practice? Download the free printable Naming Alkanes Worksheet with answer key above.