Question

Specify which atoms, if any, bear a formal charge in the Lewis structure given and the net charge for the species.

Be sure to answer all parts.

:C-----N:

Formal charge C:

Formal charge N:

Net charge:

Answer 1

Formal charge on C: (-1)

Formal charge on N: (0)

Net charge: (-1)

Explanation :

First we have to determine the Lewis-dot structure of
`CN^-`.

Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.

In the Lewis-dot structure the valance electrons are shown by 'dot'.

The given molecule is,
`CN^-`

As we know that carbon has '4' valence electrons and nitrogen has '5' valence electrons.

Therefore, the total number of valence electrons in
`CN^-` = 4 + 5 + 1= 10

According to Lewis-dot structure, there are 6 number of bonding electrons and 4 number of non-bonding electrons.

Now we have to determine the formal charge for each atom.

Formula for formal charge :

`\text{Formal charge}=\text{Valence electrons}-\text{Non-bonding electrons}-\frac{\text{Bonding electrons}}{2}`

`\text{Formal charge on C}=4-2-(6)/(2)=-1`

`\text{Formal charge on N}=5-2-(6)/(2)=0`

Net charge = -1 + 0 = -1