Water Molecule

[Fionna Shue 4L]

For H2O, why are the two lone pairs next to each other? If lone pair- lone pair repulsion is the strongest, why aren't the two lone pairs on opposites sides of each other?

[Jessica Chen 1F]

The two lone pairs look like they are next to each other (and therefore closer) when you draw them in 2D, but because it is a tetrahedral shape, all the angles/positions are technically the same distance from each other and it doesn't matter where the two lone pairs are located.

[Jordan Y4D]

A molecule with 4 regions of electron density, such as water, will always be tetrahedral in nature. Water has a tetrahedral shape, where 2 of the molecules are replaced with lone pairs, giving you a bent shape. The lone pairs are only next to each other because that is how the tetrahedral shape works, all atoms in a tetrahedral shape are adjacent.

[Chloe Likwong 2K]

It is helpful to know about electron geometry since the two comments above are pertaining to that.

Electron Geometry: takes into account the lone pairs of the central atom (thus, it is considered to be a tetrahedral)
Molecular Shape: considers bonded pairs only of the central atom (thus, its shape is bent)