Discuss the nature of bonding of compounds of group 13, 14 and 15 elements.
Answers
JEEIIT JEE Study MaterialGroup 13 Elements
Group 13 Elements (Boron Family)
What are Group 13 Elements?
The group 13 elements are the first group in the p-block of the periodic table. All the elements of group 13 are also called the boron family. The periodic table is segregated into s, p, d and f-blocks. This segregation is done based on the valence electron, if the valence electron falls on the p subshell, it comes in p-block and so on.
The members of Group 13 elements are:
Boron
Aluminium
Gallium
Indium
Thallium
The general electronic configuration for the
group 13 elements is ns2 np1.
What are Group 14 Elements?
The group 14 elements are the second group in the p-block of the periodic table. It is also called the carbon group. The members of this group are:
Carbon (C)
Silicon (Si)
Germanium (Ge)
Tin (Sn)
Lead (Pb)
Flerovium (Fl)
As all the elements in group 14 have 4 electrons in the outermost shell, the valency of group 14 elements is 4. They use these electrons in the bond formation in order to obtain octet configuration.
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.
Chemical Properties and Oxidation State of group 15 elements
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 an 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 the +5 state also decreases as we move down the group. BiF5 is the only well-characterized Bi(V) compound.
Due to the 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 oxo acids.
In nitrogen, the oxidation states from +1 to +4 tend to disproportionate in acidic solution. In the 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.