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General trends in group 15elements
(i) Electronicconfiguration: All the elements in group 15 have 5 valence electrons.Their general electronic configuration is ns2 np3.
(ii) Oxidationstates: All these elements have 5 valence electrons and require threemore electrons to complete their octets. However, gaining electrons is verydifficult as the nucleus will have to attract three more electrons. This cantake place only with nitrogen as it is the smallest in size and the distancebetween the nucleus and the valence shell is relatively small. The remainingelements of this group show a formal oxidation state of −3 in their covalentcompounds. In addition to the −3 state, N and P also show −1 and −2 oxidationstates.
All the elements present in thisgroup show +3 and +5 oxidation states. However, the stability of +5 oxidationstate decreases down a group, whereas the stability of +3 oxidation stateincreases. This happens because of the inert pair effect.
(iii) Ionizationenergy and electronegativity
First ionization decreases on movingdown a group. This is because of increasing atomic sizes. As we move down agroup, electronegativity decreases, owing to an increase in size.
(iv) Atomicsize: On moving down a group, the atomic size increases. This increasein the atomic size is attributed to an increase in the number of shells.