Explain the anomalous nature of nitrogen in group - 15.

Explanation

Anomalous properties of Nitrogen : Nitrogen differs from the remaining elements of this group due to its small size, high electronegativity, higgh ionisation enthalpy and non-availability of d-orbitals.
Nitrogen gas exists as diatomic molecule. Dut to the presence of triple bond between base N - Atoms bond dissociation energy is high (941.4 KJ/mole). Hence nitrogen is inert and unreactive.
Explanation :
`to` The single N-N bond is weaker than the single P-P bond due to high inter electronic repulsion of the non-bondding electrons in `N_(2)` because of small bond length. Therefore the catenation property is weaker in nitrogen as compound to phosphorus.
`to` Nitrogen does not form penta halides due to lack of d-orbitals.
`R_(3)P=O` exist but `R_(3)N=O` does not.
Explanation :
`to` Nitrogen does not form `d pi-P pi` multiple bond with oxygen because of lack of d - orbitals in Nitrogen atom. But in case of `R_(3)N=O` the value of nitrogen should be 5. So these compounds do not exist where as in case of 'P' atom d-orbitals are available. So P-atom can able to form `d pi-P pi` multiple bonds hence `R_(3)P=O` exist.