Bond Angle of Sulfite Ion

[Esther Ahn 4I]

In lecture Dr. Lavelle mentioned that although sulfite has 4 electron pairs arranged tetrahedrally the O-S-O bond angles are 106 degrees and not the expected 109.5 degrees. Can someone please explain why?

[Jack Mitchell 3J]

When there is a lone pair of electrons, they have a greater repulsion against the two atoms, so the two Oxygen atoms will be closer together because the lone pair is pushing them closer.

[Kailey Nichols 4B]

Similar to how the lone pair of electrons in water cause the bond angle between the H atoms to be less than 109.5 degrees, the lone pair of electrons causes the O-S-O angles to also be less than 109.5 degrees (since lone pair-bonding repulsion is stronger than bonding-bonding repulsion and thus the lone pair of electrons in SO₃^2- pushes the O atoms closer)