Question

Hydrogen azide (HN3) is a shock-sensitive liquid, which means it explodes when subjected to a physical shock. The HN3 molecule contains two N-N bonds with bond lengths 113 pm and 124 pm. The H-N-N bond angle is 112°. Draw two Lewis structures of HN3 that obey the octet rule. What is the formal charge of each atom in your structures? Which structure is most consistent with the experimental data?

Answer 1

Lewis structure of Hydrazoic acids are following:

Formal charge: The difference between the number of electrons assigned to an atom in a molecule and the number of electrons it has in its outer shell in its elemental state. Formal charge can be calculated using the formula:

F = Z – S /2 -U

           

Here;

F = formal charge

Z= group number of the atom

S = number of electrons the atom is sharing with other

U = the number of unshared electrons

For Ist N atom:

F = 5-4/2 -2=+1

Foe second N atom:

F = 5-8/2-0=+1

For third Na tom:

F = 5-6/2 -2 =0

For H atom:

F = 1-2/2-0=0

Given that;

The HN3 molecule contains two N-N bonds with bond lengths 113 pm and 124 pm. The H-N-N bond angle is 112° means both N-H bonds are different and The H-N-N bond angle is 112° means shows that the structure is bent not linear. Structure II is most consistent with the experimental data.