Explain the nature of C - X bond in alkyl halides.

Explanation

Halogen atoms are more electronegative than carbon, therefore, carbon - halogen bond of alkyl halide is polarised, the carbon atom bears a partial positive charge whereas the halogen atom bears a partial negative charge.
As we go down the group in the periodic table, the size of halogen atom is the smallest and iodine atom is the largest. Consequently the carbon - halogen bond length also increases from C - F to C - I.

Order of dipole moment :
`CH_(3)Cl gt CH_(3)F gt CH_(3)Br gt CH_(3)I`
Order of bond enthalpies :
`CH_(3)F gt CH_(3)Cl gt CH_(3)Br gt CH_(3)I`