Question

Which of the following represents the Lewis structure of ${{\text{N}}_2}$ molecule?
A) $_ \bullet ^ \bullet {\text{N}} \equiv {\text{N}}_ \bullet ^ \bullet$

B) $$_ \bullet ^ \bullet \mathop {{\text{N}}}\limits^{ \bullet {\text{ }} \bullet } =\mathop {\text{N}}\limits^{ \bullet {\text{ }} \bullet}$$$_ \bullet ^ \bullet$

C) $$_ \bullet ^ \bullet \mathop {\text{N}}\limits_{ \bullet {\text{ }} \bullet }^{ \bullet {\text{ }} \bullet } - \mathop {\text{N}}\limits_{ \bullet {\text{ }} \bullet }^{ \bullet {\text{ }} \bullet}$$$_ \bullet ^ \bullet$

D) $$_ \bullet ^ \bullet \mathop {\text{N}}\limits_{ \bullet {\text{ }} \bullet }^{ \bullet {\text{ }} \bullet } = \mathop {\text{N}}\limits_{ \bullet {\text{ }} \bullet }^{ \bullet {\text{ }} \bullet}$$$_ \bullet ^ \bullet$

Answer 1

In Lewis dot structure only that electrons are shown which are valence electrons. Nitrogen is a triatomic molecule and hence will have 3 bonds.

Complete answer:
The atomic number of nitrogen is 7. This means it has 5 electrons in its valence shell and 2 electrons are present in the valence shell. It exists in a dimer state that means it is attached with other nitrogen. The bond order in a molecule of nitrogen is 3 that means a triple bond exists in a molecule of nitrogen. After using 3 electrons for bond formation each nitrogen atom will have 2 electrons left as valence electrons. Hence the lewis dot structure will include 2 electrons on each nitrogen atom and ion triple bond between two nitrogen atoms. This is correctly represented by option A.

Hence, the correct option is A.

Additional information:
Nitrogen is colourless and odourless gas. It is the first member of group 15 and is also called pnictogens. It is abundantly present in the earth crust. About seventy eight percent of earth crust constituent nitrogen. We usually encounter nitrogen in all the living organisms. It is prime constituents in amino acids which are present in all organisms. It is a part of nucleic acid such as DNA and RNA. It is present in the human body as three percent by mass approximately.

Note: Liquid nitrogen is used as a cryogenic liquid. It acts as a coolant just like dry ice or solid carbon dioxide. Due to very high bond order it is very stable and it does not support combustion.