Electron density of lone pairs

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

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Shirley Liu 2I
Posts: 64
Joined: Fri Sep 28, 2018 12:16 am

Electron density of lone pairs

Postby Shirley Liu 2I » Mon Nov 19, 2018 12:02 pm

Why aren't lone pairs on non-central atoms in molecules considered in the VSEPR model? Don't they contribute to repulsion between atoms as well?

EllaBerry
Posts: 68
Joined: Fri Sep 28, 2018 12:29 am

Re: Electron density of lone pairs

Postby EllaBerry » Mon Nov 19, 2018 12:32 pm

The don't contribute because the non-central atoms aren't bonded to multiple atoms. Therefore there isn't an 'angle' created by the repulsion like there is with the central atom.

Jonas Talandis
Posts: 60
Joined: Fri Sep 28, 2018 12:16 am

Re: Electron density of lone pairs

Postby Jonas Talandis » Mon Nov 19, 2018 12:41 pm

Think about it as if you saw the shape of the molecule blown up in size, like when Lavelle took off an atom from the Trig. Bipyramidal shape to demonstrate the see saw shape. You can't "see" Lone pairs, so they shouldn't contribute to the shape of the molecule since there is no atom being bound there. More important to know how they affect the bond angles.

305115396
Posts: 30
Joined: Fri Sep 28, 2018 12:16 am

Re: Electron density of lone pairs

Postby 305115396 » Mon Nov 19, 2018 12:42 pm

Atoms of the non-central atoms are often only bonded with the central atom while the central atom is bonded to multiple atoms. Hence, the lone pairs on the central atom affect all of the atoms surrounding it but the lone pairs on the non-central atoms have no other atoms to affect.


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