1. Primary, Secondary, and Tertiary Molecules

2. Primary, Secondary, and Tertiary Alcohols
Ethanol is an example of a primary alcohol.
Primary alcohols contain two hydrogen atoms, and one alkyl group bonded to the carbon atom that contains the alcohol group.
Secondary alcohols contain one hydrogen atom, and two alkyl groups bonded directly to the carbon containing the alcohol.
Tertiary alcohols contain three alkyl groups, and no hydrogen atoms bonded to the carbon atom containing the alcohol group.

3. Primary, Secondary, and Tertiary Alcohols

4. Primary, Secondary, and Tertiary Halogenoalkanes
The same situation exists for halogenoalkanes
Instead of the hydroxyl groups, the halogenoalkanes contain a halogen atom

5. Primary, Secondary, and Tertiary Halogenoalkanes