# Formal Charge of Nitrate (NO_{3}^{–})

The nitrate ion (NO_{3}^{–}) consists of a nitrogen (N) atom with five valence electrons and three oxygen (O) atoms, each having six valence electrons. Nitrogen shares a double covalent bond with one oxygen atom (O=N^{+}) and two single covalent bonds (O^{–}-N^{+}) with the remaining two oxygen atoms. Its molecular structure is shown below.

To find the formal charge of NO_{3}^{–}, let us calculate the formal charges on the atoms.

**Nitrogen**

V = 5, N = 0, B = 8

Therefore,

q_{f} = 5 – 0 – 8/2 = 1

The formal charge on N in NO_{3}^{– }is 1.

**Oxygen 1 and Oxygen 2**

V = 6, N = 6, B = 2

Therefore,

q_{f} = 6 – 6 – 2/2 = -1

The formal charge on two of the oxygen atoms in NO_{3}^{– }is -1.

**Oxygen 3**

V = 6, N = 4, B = 4

q_{f} = 6 – 4 – 4/2 = 0

The net formal charge is: -1 + (2 x -1) + 0 = -1

The formal charge of NO_{3}^{–} is -1.