Bond Angle with Lone Pairs

[Sarah Zhari 1D]

Why are bond angles smaller when there are lone pairs of electrons present? For example, why are the bond angles in a tetrahedral structure larger than the bond angles in a trigonal pyramidal structure?

[Jamie Lee 1F]

The lone pairs repel the bonded molecules more, thus pushing them together and lessening the bond angles.

[Rebekah Alfred 1J]

The lone pairs on the central atom influence molecular shape and, thus, affect the bond angles. Specifically, the addition of lone pairs force the bonding electrons closer together, making the bond angles smaller.

[cassidysong 1K]

lone pairs have a greater repelling force, therefore forcing the bonding electrons closer together and therefore decreasing the bond angle slightly