Molecular Shape of H20

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

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Molecular Shape of H20

Postby DTingey_1C » Sun Nov 17, 2019 8:55 pm

H20 has a angular, bent shape to it, which is why its polar. But, why don't its lone pairs repel each other and give it a linear shape (where the lone pairs are 180 degrees from each other and the H atoms are 180 degrees from each other)? Like this:

H-- O --H

LP = lone pair
O and H = atoms
_____ is added to make LP be above the O atom

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Re: Molecular Shape of H20

Postby sbeall_1C » Sun Nov 17, 2019 8:59 pm

H2O has a bent molecular shape rather than a linear shape because the two pairs of lone pair electrons take up more space than a bond, and the electron repulsion pushes away from the atoms to create bond angles less than 180 degrees but rather less than 109.5. The Lone pair electrons will not stay in place directly on either side of the O atom to create a linear shape, but rather due to repulsion will expand.

KTran 1I
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Re: Molecular Shape of H20

Postby KTran 1I » Sun Nov 17, 2019 9:38 pm

The molecular shape for H2O is bent because the lone pairs will repel each other more than they repel the bonded pairs. Most often Lewis structures of H2O are drawn with the two lone pairs angled above the oxygen, so this might be a more helpful way of drawing the structure so you remember that the shape is bent.

Indy Bui 1l
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Re: Molecular Shape of H20

Postby Indy Bui 1l » Sun Nov 17, 2019 9:40 pm

The lone pairs cannot be on opposite sides of each other, this is due to the nature of tetrahedral shapes. if you put two lone pairs into a tetrahedral they will always be next to each other, not on opposite sides. Its hard to draw a tetrahedral model on here but looking one up might be helpful.

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