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lone pairs

Posted: Tue Nov 20, 2018 1:35 pm
by Jennifer Lathrop 1F
Do lone pairs on non central atoms affect the shape of the molecule?

Re: lone pairs

Posted: Tue Nov 20, 2018 1:48 pm
by Tam To 1B
I believe lone pairs on non central atoms would affect the polarity of the molecule and create a dipole, but it shouldn't affect the overall shape of the molecule.
For example, with CH2F2 has a tetrahedral shape. However, F has lone pairs. This would just mean that the molecule is polar, but the shape remains the same.

Re: lone pairs

Posted: Tue Nov 20, 2018 2:20 pm
by Jamie Hsu
Lone pairs on non central atoms should not affect the shape of the molecule

Re: lone pairs

Posted: Tue Nov 20, 2018 3:06 pm
by Meachelle_Lum_1I
No, I believe only lone pairs on central atoms would affect the shape. This is why the trigonal pyramidal shape (3 bonded and 1 lone pair) has a bond angle that’s slightly less than a tetrahedral (4 bonded and 0 lone pair) bond angle of 109.5 degrees.
Lone pairs on non central atoms do affect the repulsion strength however. Lone-lone>lone-bond>bond-bond.

Re: lone pairs

Posted: Tue Nov 20, 2018 3:08 pm
by Sameen Mahmood 3D
They affect neighboring atoms slightly by pushing on them but they don't create significant changes in bond angle (think CH4 vs. CH3Cl).