Question

Write down name of functional group – X.

Answer 1

We know that in organic chemistry, the functional groups are specific groups of atoms within molecules arranged in a specific manner. The following tables list common functional groups arranged by heteroatom. The symbols R, R', R'' and R''' usually denote a hydrocarbon chain or a hydrogen but they can sometimes be any group of atoms and the symbol X denotes a halide such as F, Br, Cl or I.

Complete answer:
The haloalkanes or alkyl halides, are the functional groups which contain a bond between a carbon (C) atom and a halogen such as F, Br, Cl or I. The prefix used to denote a halogen is ‘halo-’. For instance, the compound CH3F can be called fluoromethane, and the prefix here is fluoro. The suffix which is used to denote a halogen is the ‘halide’. For example, the same compound, fluoromethane (CH3F) can also be referred to as methyl fluoride, and the suffix here being fluoride.
The carbon-halogen bond varies in strength and stability based on the halogen. For example, the carbon-iodine bond in alkyl iodides is very weak but the carbon-fluorine bond in alkyl fluorides is very strong and stable too.
Excluding these alkyl fluorides, all the alkyl halides readily undergo elimination reactions or nucleophilic substitution reactions.

Note:
In the field of organic chemistry, functional groups are the substituent atoms or groups of atoms that are attached to specific molecules. The presence of a functional group in a molecule implies that the behaviour and the chemical reactions of the molecule in question can be predicted in a systematic fashion.