Identify functional groups and apply IUPAC rules to name and draw structural formulas for the main families of organic compounds

What this dot point is asking

Organic chemistry is the chemistry of carbon compounds. Carbon forms four covalent bonds and chains, branches and rings, so the number of possible structures is enormous. To bring order, compounds are grouped into homologous series: families with the same functional group, the same general formula, and a $\text{CH}_2$ difference between successive members, showing a gradual trend in physical properties.

The functional groups you must know

IUPAC naming rules

A systematic name is built in a fixed order.

1. Identify the principal functional group and choose the longest continuous carbon chain that contains it. This chain gives the stem (meth-, eth-, prop-, but-, pent-, hex-) and the suffix.
2. Number the chain so the principal functional group (or, for alkanes, the first branch point) gets the lowest possible locant.
3. Name substituents (branches like methyl, ethyl; halogens like chloro, bromo) as prefixes, each with its locant.
4. Order the prefixes alphabetically, use di-, tri-, tetra- for repeats (ignored when alphabetising), put hyphens between numbers and letters and commas between numbers.

Worked names

$\text{CH}_3\text{-CH(OH)-CH}_2\text{-CH}_3$

Principal group is -OH (alcohol, suffix -ol). Longest chain containing it is four carbons (butan-). Number for the lowest locant: the OH is on C2. Name: butan-2-ol.

$(\text{CH}_3)_2\text{CH-CH}_2\text{-COOH}$

Principal group is -COOH (carboxylic acid), so its carbon is C1. The longest chain containing it has four carbons (butanoic acid) with a methyl on C3. Name: 3-methylbutanoic acid.

$\text{CH}_3\text{-CH}_2\text{-COO-CH}_3$

This is an ester. The alkyl group from the alcohol comes first (methyl), the acyl part from the acid takes the -oate suffix (propanoate). Name: methyl propanoate.

Representing structures

You should be able to draw structures three ways: a full structural formula (every bond shown), a condensed structural formula (e.g. $\text{CH}_3\text{CH}_2\text{CH}_2\text{OH}$, branches in brackets), and a skeletal formula (carbons at line vertices and ends, carbon-hydrogens implied, heteroatoms drawn). The examination usually accepts any clear unambiguous structure unless one type is specified.

When answering nomenclature questions in the WACE examination, always pick the longest chain that includes the main functional group (not simply the longest chain), and number for the lowest locant on the principal group.