GROUP 15 ELEMENTS contain N, P, As, Sb & Bi
Their General electronic configuration: ns2np3
Dinitrogen is a diatomic gas while all others are solids.
N & P are non-metals.
As & Sb metalloids & Bi is a metal .This is due to decrease in ionization enthalpy & increase in atomic size.
Electronegativity decreases down the group.
Common oxidation states : -3, +3 & +5.
Due to inert pair effect, the stability of +5 state decreases down the group and stability of +3 state increases.
In case of nitrogen all oxidation states from +1 to +4 tend to disproportionate in acid solution for eg:- 3HNO2 –> HNO3 + H2O + 2NO
Anamalous behaviour of nitrogen –
due to its small size, high electronegativity, high ionization enthalpy and absence of d-orbitals. N2 has unique ability to form pπ-pπ multiple bonds where as the heavier members of this group do not form pπ-pπ bond because their atomic orbitals are so large & diffuse that they cannot have effective overlapping. Nitrogen exists as diatomic molecule with triple bond between the two atoms where as other elements form single bonds in elemental state. N cannot form dπpπ bond due to the non-availability of d-orbitals where as other elements can.
TRENDS IN PROPERTIES
Stability – NH3>PH3>AsH3>SbH3>BiH3.
Bond dissociation enthalpy – NH3>PH3>AsH3>SbH3>BiH3
Reducing character – NH3<PH3<AsH3<SbH3<BiH3
Basic character – NH3>PH3>AsH3>SbH3>=BiH3.
Acidic character – N2O3> P2O3> As2O3> Sb2O3> Bi2O3