repulsion

[Dakota_Campbell_1C]

Why do the lone pairs on the central atom have more repulsion than all of the valence electrons on the other atoms of the molecule? Why do the lone pairs on the central atom dictate shape.

[Shash Khemka 1K]

Lone pairs dictate the shape of a central atom because they are providing a charge that alters the shape of the structure through repulsions. A way I think about it is that the lone pair is pushing on that central atom, moving it up/down/side-to-side, causing the entire structure to alter its shape. Hope this helps!

[Matthew Choi 2H]

The electrons in a lone pair have more energy than bonded electrons because they are free and not restricted to a bond. Therefore, they repel each other more because they are more excited and take up more space. This is why they decrease bond angles and slightly distort the molecular geometry of molecules.

[Angela Cong 3C]

In bonding and vsepr models, the central atom dictates shape since its the atom that pairs with all other valence electrons. The other lone pairs are not significant enough in repulsion to affect the shape since they are essentially on the outskirts of the atom. The lone pairs on the central atom however has enough repulsion to move the bonds away from the lone electrons, thus affecting the shape