1. Phosphorous exhibit covalent character though it can accept three electrons to form phosphides. The covalent character decreases as we move down the group. that is
Phosphorus (P) > Arsenic (As) > Antimony (Sb) > Bismuth (Bi)
2. Group 15 element Forming Hydrides
3. Group 15 element Forming Halides
The group 15 elements form two series of halides of the type MX3 and MX5.Nitrogen does not form pentahalides because of the absence of d-orbitals in nitrogen. Trihalides are pyramidal in shape and the central atom is in sp3 hybridised state. In pentahalides of group 15 elements, the central atom is in sp3 d hybridization and has trigonal bipyramidal geometry. Phosphorus trichloride ( PCl3) fumes in moist air because of its reaction with water producing HCl.
PCl3 + 3H2O ------------> H3PO3 + 3HCl
Phosphorus pentachloride (PCl5) fumes in air beacuse it react with water to give initially POCl3 and finally H3PO4
PCl5 + H2O -----------> POCl3 + 2HCl
POCl3 + 3H2O -----------> H3PO4 + 3HCl
4. Group 15 element Forming Oxides
Nitrogen forms five oxides with oxidation state ranging from +1 to +5. They are N2O (Nitrous oxide), NO (Nitric Oxide), N2O3 (Dinitrogen trioxide), N2O4 (Dinitrogen tetroxide) and N2O5 (Dinitrogen pentoxide). Other elements of group 15 form two types of oxides of the type M2O3 and M2O5 (M=P,Sb or Bi. Due to reluctance of P,As,Sb and Bi to form pie-pie multiple bonding, their oxides have cage like structure and exist as dimmers (M4O6 and M4O10).
For more chemistry article visit Trends in chemical reactivity of Group 14 elements