Question

Which of the following elements shows maximum valency?
A) Carbon
B) Barium
C) Nitrogen
D) Sulphur

Answer 1

The answer is dependent on the calculation of valency, calculation that is the total number of covalent bonds it is capable of except for the lone pair of electrons.

Complete answer:
In our lower classes we have studied about the electronic configuration of atoms based on the atomic number. It is based on this concept that the valence electrons can be identified.
- Electronic configuration gives the information of electrons in the various shells and the outermost electrons gives the valency.
- Therefore, valency of an atom can be defined as the electrons that are present in the outermost shell which is associated with the formation of a chemical bond if the outer shell is not closed.
Thus, the carbon atom with the outer shell electronic configuration of carbon is $2{{s}^{2}}2{{p}^{2}}$. Thus the excited state contains four unpaired electrons which are capable of forming four covalent bonds with no lone pair of electrons.
Similarly, valency of barium is two as the outer shell electronic configuration of barium is$\left[ Xe \right]6{{s}^{2}}$
Also the valency of Nitrogen is three but it has the capacity to form dative bonds as it has a lone pair of electrons on it. It has outer shell configuration is$\left[ He \right]2{{s}^{2}}2{{p}^{3}}$
Now, valency of sulphur atom six with outer shell configuration as $3{{s}^{2}}3{{p}^{4}}$

Therefore, the correct answer is option D) Sulphur.

Note: Note that the valency of an atom is one which measures the number of covalent bonds formed but not the dative bond which is also a covalent bond formed by extra electrons on the atom.