15.1.2—Classify halogenoalkanes into primary,

A primary halogenoalkane has the C–X carbon attached to one other carbon, secondary to two, and tertiary to three. The classification does not count the halogen itself.

Locate the carbon directly bonded to X, then count its carbon neighbours. This classification helps predict substitution mechanism and relative reaction rate.

CH₃CH₂Br is primary; CH₃CHBrCH₃ is secondary; (CH₃)₃CBr is tertiary. The carbon skeleton, not the name ending alone, determines the label.

Do not classify by the total number of carbons in the molecule, and do not call a carbon attached to two hydrogens “secondary”.