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VSEPR (lone pairs taking axial vs equatorial positions)

Posted: Thu Nov 29, 2018 8:05 pm
by Steven Garcia 1H
Why do the lone pairs of a molecule with let's say a VSEPR formula AX4E2 take the positions of the axial atoms, whereas the lone pairs of a molecule with a VSEPR formula AX3E2 take the positions of the equatorial atoms?

Re: VSEPR (lone pairs taking axial vs equatorial positions)

Posted: Thu Nov 29, 2018 9:23 pm
by spark99
When there is a lone pair, the molecule has to be the in the best optimum position available so that the electrons are equally spread apart. So for example, when there is a lone pair in a AX3E2, the best optimum place for the lone pair is in the equitorial axes.

Re: VSEPR (lone pairs taking axial vs equatorial positions)

Posted: Fri Nov 30, 2018 9:23 am
by Eunice Lee 1A
In addition, say we replace the lone pairs in AX4E2 with bonded atoms, making it AX6. This molecule is square bipyramidal, which has 90-degree bond angles all around. The atoms replaced with the lone pairs aren't necessarily the axial atoms because the molecule is symmetrical in all directions.