Final answer:
In alkane halogenation, the halogen atom abstracts a hydrogen atom from the alkane molecule.
Step-by-step explanation:
In the first propagation step of the radical chain mechanism of alkane halogenation, the halogen atom actually abstracts a hydrogen atom from the alkane molecule. This happens because halogens are more electronegative than hydrogen, which means they have a stronger pull on electrons.
When a halogen approaches an alkane, it can attract the shared electron pair between the hydrogen and carbon atoms, leading to the abstraction of the hydrogen atom and formation of a new C-H bond. This is a key step in alkane halogenation reactions.