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Nitrosonium ion (NO⁺) Lewis structure

10 valence electrons, linear, a charge of +1

N O + +
NO⁺ as the Lewis Structure Generator draws it: lone pairs as dots, nonzero formal charges circled.

Build NO⁺ step by step in the Lewis Structure Generator

What is the Lewis structure of NO⁺?

Nitrosonium ion, NO⁺, has 10 valence electrons. Its two atoms are joined by one N≡O triple bond. It carries one lone pair on the N and one on the O. Its only formal charge is +1, on the O. As two atoms it is linear.

Valence electrons in NO⁺

Element Group Valence electrons Atoms Electrons
Nitrogen 15 5 1 5
Oxygen 16 6 1 6
Charge of 1+ −1
Total 10

In one line: 5 + 6 − 1 = 10. Each atom brings the valence electrons its group gives it, and the positive charge takes one away for each unit.

How to draw the NO⁺ Lewis structure

  1. Count the valence electrons. Valence electrons: N 5 and O 6, and the 1+ charge takes 1 away. 5 + 6 − 1 = 10.
  2. Join the two atoms. With only two atoms there is no choice to make: they bond to each other.
  3. Join the atoms with single bonds. One single bond uses 2 electrons, leaving 10 − 2 = 8.
  4. Complete the outer atoms. The outer O takes 6 electrons as lone pairs to reach eight, leaving 8 − 6 = 2.
  5. Put the rest on N. The 2 left go as one lone pair on N, and N now has 4 electrons round it.
  6. Make multiple bonds where needed. N has only 4 electrons, so two lone pairs move into the bond, making an N≡O bond, and N now has 8.

Lone pairs and formal charges in NO⁺

Atom Number Bonds Lone pairs Electrons round it Formal charge, V − N − B/2
N 1 one triple bond 1 8 5 − 2 − 3 = 0
O 1 one triple bond 1 8 6 − 2 − 3 = +1

V is the atom’s valence electrons, N its nonbonding electrons and B its bonding electrons. The formal charges add up to +1, the charge on the ion.

Shape and polarity of NO⁺

Central atom none, two atoms
Electron geometry linear
Molecular geometry linear
Ideal bond angle none, two atoms
Polarity, an estimate not applicable

An ion carries a net charge, so whether its bond dipoles cancel is not the question polarity asks.

NO⁺ Lewis structure compared with its molecular orbital diagram

Lewis structure Molecular orbital diagram
Bond order 3 3
Unpaired electrons 0 0

In the molecular orbital diagram NO⁺’s 10 valence electrons put 8 in bonding orbitals and 2 in antibonding ones, so its bond order is (8 − 2)/2 = 3. The Lewis structure gives the same bond order and the same number of unpaired electrons. The measured bond length is 106 pm (Huber and Herzberg, Constants of Diatomic Molecules, 1979). The Molecular Orbital Diagram Visualizer draws the diagram level by level.

Work with NO⁺