NF3 Lewis Structure
Nitrogen trifluoride · An etching gas in electronics manufacturing, and a potent greenhouse gas.
The NF3 Lewis structure has 26 valence electrons, drawn as three N–F bonds, with ten lone pairs in total. The central N is sp3 hybridized, which makes it a trigonal pyramidal molecule with a bond angle of 107 degrees. NF3 is polar: the N-F bonds are polar, and the lone pair on the central atom bends the molecule out of shape, so the dipoles do not cancel.
- 26 valence e−
- trigonal pyramidal
- ≈107° bond angle
- sp3
- polar
NF3 molecular geometry
Trigonal pyramidal, from 4 electron domains on the central N: 3 bonded atoms and 1 lone pair (AX3E1). The electron geometry is tetrahedral; the shape is what is left when the lone pairs are not counted as atoms. Wedges point toward you, hashed wedges away. Every shape in the VSEPR chart →
Calculated properties
| Total valence electrons | 26 |
|---|---|
| Bonding electrons | 6 (3 shared pairs) |
| Nonbonding electrons | 20 (10 lone pairs) |
| Lone pairs on N | 1 |
| Electron domains (steric number) | 4 |
| VSEPR notation | AX3E1 |
| Electron geometry | tetrahedral |
| Molecular geometry | trigonal pyramidal |
| Bond angle | ≈107° |
| Hybridization | sp3 |
| Polarity | polar |
| Formal charges | all zero |
| Resonance structures | none |
| Molar mass | 71.001 g/mol |
N Nitrogen 5 valence e− F Fluorine 3 atoms, 7 valence e− each
How to draw the NF3 Lewis structure
Step through it. The bar shows how much of the 26-electron budget is spent at each stage - it never grows, which is the whole constraint.
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Skeleton. Join every connected pair with one bond. 3 bonds spends 6 electrons.
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Outer octets. Spend electrons as lone pairs on the outer atoms until each has eight. 2 are still unplaced.
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Centre. Everything still unplaced goes on N, which now has 8 electrons around it.
The reasoning at each step
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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.
5 (N) + 3 x 7 (F) = 26 valence electrons -
Choose the central atom
N is the least electronegative atom here, so it takes the centre. Hydrogen is never central: it can only form one bond.
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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.
3 bonds x 2 = 6 electrons used, 20 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 20, has 20, exactly enough -
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.
N: 1, F1: 3, F2: 3, F3: 3 (20 electrons) -
Check the central atom
N ends up with a full octet. Every electron in the budget is now placed.
N: 6 bonding + 2 nonbonding = 8 -
Check the formal charges
Formal charge is valence electrons, minus lone-pair electrons, minus the number of bonds. Every atom here comes out at zero, which is the sign of a good structure.
all formal charges = 0 -
Work out the shape
Count the electron domains on N: 3 bonded groups plus 1 lone pair. A double or triple bond still counts as one domain, because it points in one direction. That gives tetrahedral electron geometry; ignore the lone pairs and the atoms themselves sit in a trigonal pyramidal arrangement. One lone pair pushes the three bonds down from the ideal 109.5 degrees.
steric number 4 -> sp3 -> trigonal pyramidal, bond angle 107 -
Decide whether it is polar
The N-F bonds are polar, and the lone pair on the central atom bends the molecule out of shape, so the dipoles do not cancel.
dipoles do not cancel -> polar
Is NF3 polar or nonpolar?
NF3 is polar. The N-F bonds are polar, and the lone pair on the central atom bends the molecule out of shape, so the dipoles do not cancel.
| Bond | Electronegativity difference | Character |
|---|---|---|
| N–F | 0.94 | polar covalent |
Common questions
How many valence electrons does NF3 have?
NF3 has 26 valence electrons. 6 of them are in bonds and 20 sit in lone pairs.
What is the molecular geometry of NF3?
NF3 is a trigonal pyramidal molecule. The central N has 3 bonded groups and one lone pair, a steric number of 4, which gives tetrahedral electron geometry and a trigonal pyramidal molecule.
What is the bond angle in NF3?
The bond angle in NF3 is 107 degrees. One lone pair pushes the three bonds down from the ideal 109.5 degrees.
What is the hybridization of NF3?
The central N in NF3 is sp3 hybridized. Steric number 4 means 4 orbitals have to be mixed, which is exactly what sp3 gives you.
Is NF3 polar or nonpolar?
NF3 is polar. The N-F bonds are polar, and the lone pair on the central atom bends the molecule out of shape, so the dipoles do not cancel.