N2O Lewis Structure
Nitrous oxide (laughing gas, dinitrogen monoxide) · A dental anaesthetic, a propellant in whipped cream, and a strong greenhouse gas.
The N2O Lewis structure has 16 valence electrons, drawn as one N≡N bond and one N–O bond, with four lone pairs in total. The central N is sp hybridized and the molecule is linear, with a bond angle of 180 degrees. N2O is polar: the atoms around the centre are not all the same, so the bond dipoles are different sizes and cannot cancel. There are two equivalent resonance structures.
- 16 valence e−
- linear
- 180° bond angle
- sp
- polar
Calculated properties
| Total valence electrons | 16 |
|---|---|
| Bonding electrons | 8 (4 shared pairs) |
| Nonbonding electrons | 8 (4 lone pairs) |
| Lone pairs on N | 0 |
| Electron domains (steric number) | 2 |
| VSEPR notation | AX2 |
| Electron geometry | linear |
| Molecular geometry | linear |
| Bond angle | 180° |
| Hybridization | sp |
| Polarity | polar |
| Formal charges | N: +1, O: -1 |
| Resonance structures | 2 |
| Molar mass | 44.013 g/mol |
How to draw the N2O Lewis structure
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Count the valence electrons
Add up the outer-shell electrons every atom brings. That total is the budget for the whole structure - every line and every dot has to come out of it, and nothing may be added.
2 x 5 (N) + 6 (O) = 16 valence electrons -
Work out what is bonded to what
Nitrous oxide is a known N–N–O chain: the two nitrogens are bonded to each other and only one of them carries the oxygen.
-
Join everything with single bonds first
Every connection starts as one shared pair. Draw them all before worrying about double bonds - the arithmetic in the next step is what tells you where the double bonds have to go.
2 bonds x 2 = 4 electrons used, 12 left -
Work out how far short you are
Add up what every atom still needs to fill its shell - eight electrons for most atoms, two for hydrogen - minus what its single bonds already give it. Compare that with the electrons you have left. The difference decides everything that follows.
needs 16, has 12, short by 4 -
Turn the shortfall into multiple bonds
Being short means atoms have to share more. Every pair that moves from a lone pair into a bond counts twice - once for each atom - so a shortfall of 4 is covered by 2 extra shared pairs. That is where the triple bond comes from.
N1#N2 -
Fill in the lone pairs
Every electron not in a bond sits as a lone pair on an atom. Each atom takes exactly what it needs to finish its shell - there is no choice left at this point.
N1: 1, O: 3 (8 electrons) -
Check the formal charges
Formal charge is valence electrons, minus lone-pair electrons, minus the number of bonds. They are not real charges, but they have to add up to the overall charge on the species, and a structure that keeps them small is the better one.
N2: 5 - 0 - 4 = +1 ; O: 6 - 6 - 1 = -1 -
Work out the shape
Count the electron domains on N: 2 bonded groups. A double or triple bond still counts as one domain, because it points in one direction. That gives linear electron geometry; ignore the lone pairs and the atoms themselves sit in a linear arrangement.
steric number 2 -> sp -> linear, bond angle 180 -
Decide whether it is polar
The atoms around the centre are not all the same, so the bond dipoles are different sizes and cannot cancel.
dipoles do not cancel -> polar
Resonance structures
More than one drawing gives the same electron count and the same formal charges, and no single one of them is the real molecule. N2O is an average of the 2 structures below, which is why bonds that look different here are actually identical in the real molecule.
Is N2O polar or nonpolar?
N2O is polar. The atoms around the centre are not all the same, so the bond dipoles are different sizes and cannot cancel.
| Bond | Electronegativity difference | Character |
|---|---|---|
| N–O | 0.40 | polar covalent |
| N–N | 0.00 | nonpolar covalent |
Common questions
How many valence electrons does N2O have?
N2O has 16 valence electrons. 8 of them are in bonds and 8 sit in lone pairs.
What is the molecular geometry of N2O?
N2O is a linear molecule. The central N has 2 bonded groups, a steric number of 2, which gives linear electron geometry and a linear molecule.
What is the bond angle in N2O?
The bond angle in N2O is 180 degrees. That is the ideal linear angle, and nothing distorts it here.
What is the hybridization of N2O?
The central N in N2O is sp hybridized. Steric number 2 means 2 orbitals have to be mixed, which is exactly what sp gives you.
Is N2O polar or nonpolar?
N2O is polar. The atoms around the centre are not all the same, so the bond dipoles are different sizes and cannot cancel.
Does N2O have resonance structures?
Yes. N2O has two equivalent resonance structures. The real molecule is not any one of them - it is an average, so every bond that differs between the drawings is really the same length in the actual molecule.