Chapter 1: Nomenclature
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There are over 100 million known organic compounds, and somehow chemists can name every single one without ambiguity. That is not magic - it is nomenclature, a systematic language built from a handful of simple rules. If you understand those rules, you can decode any IUPAC name the MCAT throws at you and instantly picture the molecule in your head.
Here is the thing most students get wrong about nomenclature: they try to memorize names. The MCAT does not ask you to name a compound from scratch. It gives you a name inside a passage and expects you to build the structure mentally, then predict how it will react. The real skill is reading a name like “3-ethyl-2-methylhexanoic acid” and immediately seeing the carbon backbone, the branching, and the carboxyl group. That is what this chapter will train you to do.
Naming is Just a Street Address
Think of IUPAC naming as writing a street address. Every address has three parts: the city tells you the general area, the street name tells you which road, and the house number tells you exactly where on that road. IUPAC names work the same way. The parent chain is the city - it tells you how many carbons form the backbone. The suffix is the street - it tells you the highest-priority functional group. The locant numbers are the house numbers - they tell you exactly where substituents and functional groups sit on the chain.
“2-methylbutane” is really just shorthand for “House 2 on Butane Street, Methyl neighborhood.” Once you see naming this way, every IUPAC name becomes a set of directions for drawing a molecule.
In This Chapter
- 1.1 IUPAC Naming - The Universal Language of Organic Chemistry
- 1.2 Identifying the Longest Carbon Chain (Parent Chain)
- 1.3 Naming Alkanes - Prefixes, Suffixes, and Substituents
- 1.4 Naming Alkenes and Alkynes - Indicating Unsaturation
- 1.5 Naming Cyclic Compounds - Cycloalkanes and Cycloalkenes
- 1.6 Naming Aromatic Compounds - Benzene Derivatives and Ortho/Meta/Para
- 1.7 Common Functional Groups - Hydroxyl, Carbonyl, Carboxyl, Amino, Phosphate
- 1.8 Naming Alcohols, Ethers, Aldehydes, Ketones, and Carboxylic Acids
- 1.9 Naming Amines, Amides, Esters, and Acid Halides
- 1.10 Substituent Priority and Numbering Rules
- 1.11 Common vs. IUPAC Names - What the MCAT Actually Tests
- 1.12 Naming Polyfunctional Compounds - Putting It All Together
- Section Test