Charge Of NO (Nitric Oxide) And Its Reactions

NO, nitric oxide, is an oxide of nitrogen. The nitrogen and oxygen atoms are held together by a covalent bond. NO is one of those compounds with incomplete octet yet it has no charge. But, both elements that make up this compound have their oxidation states.

Nitric oxide is an intermediate product formed in the Ostwald process, the oxidation of ammonia to nitric acid. The chemistry of NO is worth looking into. How is it a neutral atom despite the incomplete octet of nitrogen and oxygen?

There’s only one way to find out why NO has no charge. Keep reading.

Properties of NO

  • Nitric oxide is a colorless and odorless gas
  • It is a diatomic molecule made of nitrogen and oxygen and has a molar mass of 30 g/mol
  • Nitric oxide is a linear molecule with double covalent bonds between the nitrogen and oxygen atoms
  • It has a bond angle of 180° and the nitrogen atom has an sp2 hybridization which gives the molecule its bent molecular geometry and polarity
  • It has a density of 1.3402 g/L, a melting point of -263°F (-164°C) and a boiling point of -242°F (-152°C)
  • Nitric oxide is not a foul-smelling gas, but it is a major contributor to air pollution

What is the charge on the NO molecule?

NO has no charge. This diatomic molecule does not have fewer or more electrons. The compound has a total of eleven valence electrons (the sum of the five and six valence electrons of nitrogen and oxygen, respectively).

The distribution of electrons will always give oxygen a complete octet and nitrogen will have seven electrons, including the unpaired electron.

Nitric oxide is a relatively unstable free radical because of its equal number of protons and electrons, and an unpaired electron. Therefore, it can form NO or NO+, based on how it reacts.

In addition, nitrogen and oxygen (two nonmetals) share four electrons, which are responsible for the double bonds between N and O.

What is the formal charge on N in NO?

Formal charge = number of valence electrons – number of non-bonding electrons – number of bonding electrons divided by 2

That is, FC = V – N – B/2

Nitrogen has 5 valence electrons, 3 non-bonding electrons, and 4 bonding electrons.

FC = 5 – 3 – 4/2

FC = 0

Therefore, nitrogen has a formal charge of 0.

What is the formal charge on O in NO?

Oxygen has 6 valence electrons, 4 non-bonding electrons, and 4 bonding electrons.

FC = 6 – 4 – 4/2

FC = 0

Therefore, the formal charge of oxygen in NO is 0.

Reactions of NO

Reaction with oxygen

Nitrogen dioxide is a product of the oxidation of nitric oxide.

 2NO + O2 → 2NO2

Reaction with water

Nitric oxide converts to nitrous acid when it reacts with oxygen and water.

4NO + O2 + 2H2O → 4HNO2

Reaction with halides

Nitric oxide combines with fluorine, chlorine, and bromine to produce nitrosyl halides.

  • 2NO + F2 → 2NOF
  • 2NO + Cl2 → 2NOCl
  • 2NO + Br2 → 2NOBr

Reaction with nitrogen dioxide

In a reversible reaction, nitric oxide reacts with nitrogen dioxide to form an intensely blue dinitrogen trioxide.

NO + NO2 ⇌ ON−NO2

Condensation reaction

Nitric oxide can condense to a liquid and dimerizes to dinitrogen dioxide. In dinitrogen dioxide, the distance between the N–N atoms in crystalline NO is 218 pm, which is almost twice the distance between N–O.

But, these bonds are weak and reversible.

Decomposition reaction

Nitric oxide will decompose into its constituent elements – nitrogen and oxygen – in an endothermic reaction.

2NO → O2 + N2


What is the difference between nitric oxide and nitrogen dioxide?

Nitric oxide is a gas at room temperature and nitrogen dioxide is a liquid at room temperature. Nitric oxide has a sharp, sweet smell, while nitrogen dioxide has a strong and offensive odor.

However, at 90°F, nitrogen dioxide becomes a reddish-brown gas with a foul odor. In addition, nitric oxide becomes nitrogen dioxide when it reacts with oxygen.

What is the oxidation number of N in NO?

The charge of N in NO is +2. Nitrogen has five electrons in its valence shell. It will either gain three more electrons or lose the five electrons, which is why it has an oxidation number of +3 or +5.

However, in nitric oxide, nitrogen is not in any of these states because it shares electrons with oxygen instead.

What is the oxidation number of O in NO?

In NO, O has an oxidation state of -2. Since N is in its +2 oxidation state and the overall charge on the compound is 0, O will have a -2 charge.


There are many compounds with incomplete octets and no charge. Nitric oxide is one of those compounds. The neutral charge of NO is because of the triple bond between the nitrogen and oxygen atoms.

Nitric oxide is an unstable free radical that can possess any charge, depending on how it behaves in a reaction. It can form NO or NO+ if it gains or losses electrons, respectively.

Also, learn about the charge of nitrate.

Thanks for reading.