Full structural formula shows all the atoms and bonds in a molecule.

Shortened structural formula shows the atoms in a molecule and gives an idea of their arrangement without showing every bond, e.g. $CH_3CH_2CH_2CH_3$.

Skeletal structural formula is a simplification where neither carbon atoms, nor any hydrogens attached to the carbon atoms, are shown. The presence of a carbon atom is implied by a ‘kink’ in the carbon backbone, and at the end of the line.

→ When counting the number of atoms for the molecular formula from skeletal formula, the number of hydrogens present can be calculated from the total number of lines at a vertex (which represents a carbon) — a carbon atom must have a total of $4$ bonds, so if fewer than $4$ lines are present then the difference is the number of hydrogens present.

Alcohols are substituted alkanes in which one or more of the hydrogen atoms is replaced with a hydroxyl functional group, $-OH$ group.

• Naming conventions for homologous series covered at Higher and National 5

Haloalkanes (alkyl halides) are substituted alkanes in which one or more of the hydrogen atoms is replaced with a halogen atom.

→ Haloalkanes can be made via a substitution reaction with an alkane. Light energy/UV light is required for this reaction to take place. They can also be formed via an addition reaction with an alkene.

2—bromo—2—chloro—1,1,1—trifluoroethane

Monohaloalkanes contain only one halogen atom. Dihaloalkanes contain two halogen atoms, and so on.

The naming conventions for haloalkanes are the same as alkanes, but the positions of each halogen on the molecule must be indicated, as is done with branches. Numbering starts from the right and halogens are given in the name in alphabetical order. Branches are given last in the name.

Monohaloalkanes can be classified as primary, secondary or tertiary according to the number of alkyl groups attached to the carbon atom containing the halogen atom.

Primary haloalkane

Secondary haloalkane

Tertiary haloalkane

The carbon-halogen bond is polar, making haloalkanes susceptible to nucleophilic attack.

Ethers can be regarded as substituted alkanes in which a hydrogen atom is replaced with an alkoxy functional group, $-OR$, and have the general structure $R-O-R’$, where $R$ and $R’$ are alkyl groups.