Alkyl radical and Chemical group

Alkyl radical noun - Any of a series of univalent groups of the general formula CnH2n+1 derived from aliphatic hydrocarbons.

Chemical group and alkyl radical are semantically related. In some cases you can use "Chemical group" instead a noun phrase "Alkyl radical".

Chemical group noun - (chemistry) two or more atoms bound together as a single unit and forming part of a molecule.

Alkyl radical and chemical group are semantically related. Sometimes you can replace phrase "Alkyl radical" with "Chemical group", this phrases are similar.