Nitrogen dioxide (NO₂) Lewis structure
17 valence electrons, bent
Build NO₂ step by step in the Lewis Structure Generator
What is the Lewis structure of NO₂?
Nitrogen dioxide, NO₂, has 17 valence electrons. Nitrogen is the central atom, joined by one N=O double bond and one N−O single bond. One electron is left unpaired, on the central N. Its formal charges are +1 on the central N and −1 on the single-bonded O. It has two equivalent resonance forms. N is AX₂E₁: bent.
Valence electrons in NO₂
In one line: 5 + 2 × 6 = 17. Each atom brings the valence electrons its group gives it.
How to draw the NO₂ Lewis structure
- Count the valence electrons. Valence electrons: N 5 and each O 6. 5 + 2 × 6 = 17.
- Choose the central atom. N goes in the middle: N is the least electronegative atom other than H, χ 3.04 against 3.44 for O. Checked the other way, O in the middle would need an O−O bond, and electronegative atoms of one element avoid bonding to each other when they can.
- Join the atoms with single bonds. Two single bonds use 4 electrons, leaving 17 − 4 = 13.
- Complete the outer atoms. Each outer atom takes enough lone pairs to reach eight: 2 O × 6 = 12, leaving 13 − 12 = 1.
- Put the rest on the central atom. The 1 left goes on N as an unpaired electron, and N now has 5 electrons round it.
- Make multiple bonds where needed. N has only 5 electrons, so one lone pair moves into the bonds, making an N=O bond, and N now has 7, one of them unpaired.
Lone pairs and formal charges in NO₂
| Atom | Number | Bonds | Lone pairs | Electrons round it | Formal charge, V − N − B/2 |
|---|---|---|---|---|---|
| N (central) | 1 | one double bond and one single bond | 0 and 1 unpaired electron | 7 | 5 − 1 − 3 = +1 |
| O | 1 | one double bond | 2 | 8 | 6 − 4 − 2 = 0 |
| O | 1 | one single bond | 3 | 8 | 6 − 6 − 1 = −1 |
V is the atom’s valence electrons, N its nonbonding electrons and B its bonding electrons. The formal charges add up to 0, the molecule’s overall charge.
Resonance structures of NO₂
The two forms differ only in where the electrons sit, so the real molecule is one structure, their average, the resonance hybrid. Two N−O bonds each have an average order of 3/2. Two O atoms share a formal charge of −1 between them, −1/2 each.
Shape and polarity of NO₂
| Central atom | N |
|---|---|
| VSEPR class | AX₂E₁ |
| Electron geometry | trigonal planar |
| Molecular geometry | bent |
| Ideal bond angle | 120° |
| Polarity, an estimate | polar |
The bent shape leaves the bond dipoles unbalanced.
N has two σ bonds and one domain holding a single electron, three electron domains in all, so its electron geometry is trigonal planar. Counting only the bonded atoms, the molecular geometry is bent.
The VSEPR Molecular Geometry viewer turns the AX₂E₁ shape in 3D, lone pairs included.
Notes on the NO₂ Lewis structure
- Courses differ on where to draw the odd electron. This tool puts it on nitrogen, the central atom, as most textbooks do; that is why nitrogen shows +1.
- One of N’s domains is a single electron, which pushes less than a pair, so the real shape sits between the ideal ones: NO₂ opens to 134°, and the methyl radical is flat.
Work with NO₂
- Lewis Structure Generator: NO₂ built step by step, with every formal charge worked out
- VSEPR Molecular Geometry: every VSEPR shape in 3D, with its bond angles
- All 78 Lewis structures: valence electrons, resonance, shape and polarity in one table