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Axial and Equatorial

Posted: Sat Nov 16, 2019 11:21 pm
by Hannah Lee 2F
What are "axial" and "equatorial" atoms? What do we need to know about them when determining molecular shaping using VSEPR?

Re: Axial and Equatorial

Posted: Sun Nov 17, 2019 12:53 am
by kpang_4H
Equatorial ones are on the x-axis or horizontal plane like an equator and axial ones are the vertical ones,

Re: Axial and Equatorial

Posted: Sun Nov 17, 2019 1:03 am
by Julie Park 1G
The difference between a molecule's "energy" when the lone pairs (e-) are put on the axial or equatorial planes can help you identify the molecule's most stable structure.

A more stable structure would be one with lower "energy" (less e- repulsion)

For example, in , there are two possible places (orientations) where the lone pair can exist (axial or equatorial)
Here, the axial lone pair strongly repels the e- pairs in the three equatorial bonds.
Or, the equatorial lone pair can sit on the molecule’s equator (plane perpendicular to axis) where it strongly repels e- pairs in the two axial bonds (giving it a see-saw shape)

Because the lone pair only repels two e- pairs in the equatorial position (meaning that it has lower energy compared to the axial position) this orientation is more stable and preferred.