Numford
Hybridisation

Hybridisation of NH₄⁺

N is sp³ hybridised (hybridization by the VSEPR count): 4 sigma bonds and no lone pairs give a tetrahedral shape, bond angle 109.5°.

HHNHH
  • N
  • H

NH₄⁺Ammonium ion

Tetrahedral

AB₄: 4 bond pairs, no lone pairs

  • Hybridisationsp³
  • Bond angle109.5°
  • Polarityion, charge +1

Why this shape

  1. N has 5 valence electrons. In the Lewis structure it makes four single bonds to H and keeps no lone pair, which leaves it a formal charge of +1.
  2. Steric number = four sigma bonds + no lone pairs = 4, so N is sp³ hybridised.
  3. Four electron pairs point to the corners of a tetrahedron (tetrahedral electron geometry). With no lone pairs the atoms take the same shape: tetrahedral.
  4. All the bond pairs repel each other equally, so the angle is the ideal 109.5°.
  5. NH₄⁺ is an ion with an overall charge of +1, so it is not described as polar or non-polar.

Lewis structure

8 valence electrons
NHHHH+

Formal charges: N +1

Working

Why this hybridisation and shape

  1. N has 5 valence electrons. In the Lewis structure it makes four single bonds to H and keeps no lone pair, which leaves it a formal charge of +1.
  2. Steric number = four sigma bonds + no lone pairs = 4, so N is sp³ hybridised.
  3. Four electron pairs point to the corners of a tetrahedron (tetrahedral electron geometry). With no lone pairs the atoms take the same shape: tetrahedral.
  4. All the bond pairs repel each other equally, so the angle is the ideal 109.5°.
  5. NH₄⁺ is an ion with an overall charge of +1, so it is not described as polar or non-polar.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Hybridisation of NH4+: quick answers

What is the hybridisation of NH4+?

N has 5 valence electrons. In the Lewis structure it makes four single bonds to H and keeps no lone pair, which leaves it a formal charge of +1. Steric number = four sigma bonds + no lone pairs = 4, so N is sp³ hybridised.

What is the shape of NH4+ and its bond angle?

Tetrahedral, with a bond angle of 109.5 degrees. Four electron pairs point to the corners of a tetrahedron (tetrahedral electron geometry). With no lone pairs the atoms take the same shape: tetrahedral. All the bond pairs repel each other equally, so the angle is the ideal 109.5°.

How many lone pairs are on the central atom of NH4+?

None. N has 5 valence electrons. In the Lewis structure it makes four single bonds to H and keeps no lone pair, which leaves it a formal charge of +1.

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