Numford
Hybridisation

Hybridisation of ClO₄⁻

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

OOClOO
  • Cl
  • O

ClO₄⁻Perchlorate ion

Tetrahedral

AB₄: 4 bond pairs, no lone pairs

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

Why this shape

  1. Cl has 7 valence electrons. It uses seven in three double bonds to O and one single bond to O, so none are left over.
  2. Steric number = four sigma bonds + no lone pairs = 4, so Cl is sp³ hybridised. A double or triple bond counts once: only its sigma bond uses a hybrid orbital.
  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. ClO₄⁻ is an ion with an overall charge of −1, so it is not described as polar or non-polar.

Lewis structure

32 valence electrons
i

Drawn with three Cl=O bonds (expanded octet). The double bonds are shared over all four O atoms by resonance.

ClOOOO−

Formal charges: O −1

Working

Why this hybridisation and shape

  1. Cl has 7 valence electrons. It uses seven in three double bonds to O and one single bond to O, so none are left over.
  2. Steric number = four sigma bonds + no lone pairs = 4, so Cl is sp³ hybridised. A double or triple bond counts once: only its sigma bond uses a hybrid orbital.
  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. ClO₄⁻ 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 ClO4-: quick answers

What is the hybridisation of ClO4-?

Cl has 7 valence electrons. It uses seven in three double bonds to O and one single bond to O, so none are left over. Steric number = four sigma bonds + no lone pairs = 4, so Cl is sp³ hybridised. A double or triple bond counts once: only its sigma bond uses a hybrid orbital.

What is the shape of ClO4- 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 ClO4-?

None. Cl has 7 valence electrons. It uses seven in three double bonds to O and one single bond to O, so none are left over.

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