Water Molecule

(Polar molecules, Non-polar molecules, etc.)

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Fionna Shue 4L
Posts: 59
Joined: Fri Sep 28, 2018 12:18 am

Water Molecule

Postby Fionna Shue 4L » Sun Nov 18, 2018 4:21 pm

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
Posts: 61
Joined: Fri Sep 28, 2018 12:17 am

Re: Water Molecule

Postby Jessica Chen 1F » Sun Nov 18, 2018 4:32 pm

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
Posts: 25
Joined: Fri Sep 28, 2018 12:27 am

Re: Water Molecule

Postby Jordan Y4D » Sun Nov 18, 2018 5:00 pm

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
Posts: 70
Joined: Fri Sep 28, 2018 12:23 am

Re: Water Molecule

Postby Chloe Likwong 2K » Sun Nov 18, 2018 9:16 pm

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)

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