Group 15 elements consist of nitrogen, phosphorus, arsenic, antimony and bismuth. As we move down the group, there is a transition from non-metallic to metallic through metalloid character. The elements nitrogen and phosphorus are non-metals, arsenic and antimony are metalloids and lastly we have bismuth which is a typical metal. The general valence shell electronic configuration of these elements is ns2np3. The s orbital is completely filled and p orbital is half filled which makes them stable in nature. The chemical properties of these elements are determined by the oxidation states exhibited by them.
Oxidation State and Chemical Properties
The elements of group 15 generally exhibit -3, +3 and +5 oxidation states. The tendency to exhibit -3 oxidation state decreases as we move down the group due to increase in the size of the atom and the metallic character. Bismuth hardly forms any compound in oxidation state -3. In fact the stability of +5 state also decreases as we move down the group. BiF5 is the only well characterized Bi(V) compound.
Due to inert pair effect, the stability of +5 state decreases and +3 state increases as we move down the group in the periodic table. Nitrogen reacts with oxygen and also exhibits +1, +2, +4 oxidation states. On the other hand phosphorus shows +1 and +4 states in some oxoacids.
In nitrogen, the oxidation states from +1 to +4 tend to disproportionate in acidic solution. In case of phosphorus the intermediate oxidation states disproportionate into +5 and -3 in both acids and alkalis. Whereas considering the case of arsenic, antimony and bismuth, the +3 state is stable with respect to disproportionation.
Nitrogen has only 4 electrons in its outermost shell (one in s orbital and 3 in p) which is available for bonding, hence it exhibits a maximum covalency of 4. The heavier elements have a vacant d orbital in the valence shell which is used for bonding.
This article deals with the oxidation states of group 15 elements. For any further query install Byju’s the learning.