Long pairs

[Amina Durrani 3G]

Why do molecules with lone pairs will have angles slightly less than what their shape would be without lone pairs?

[Ethan Lam 4A]

Molecules with lone pairs have smaller bond angles because of the electron repulsion from the lone pairs that pushes other atoms away.

[Angus Wu_4G]

This is because when there is a lone pair, the lone pair occupies a larger space and causes electron-electron repulsion, forcing all the other regions of electron density closer to each other and farther away from the lone pair. This is why the bond angle in molecules with a lone pair is slightly less than without a lone pair.

[Tiffany Chao 2H]

Lone pairs create a strong electron-electron repulsion which pushes all other atoms closer to together. For example, if you had a trigonal pyramidal with a lone pair at the top, it would push the atoms that are part of the structure closer together, creating a smaller bond angle between the atoms.