Tetrahedral vs Trigonal Pyramid

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Tylor McGrew 1J
Posts: 20
Joined: Fri Sep 29, 2017 7:03 am

Tetrahedral vs Trigonal Pyramid

Postby Tylor McGrew 1J » Sun Nov 12, 2017 5:17 pm

I am confused as to when a Lewis Structure is identified as Tetrahedral or Trigonal Pyramid. Both have 4 bonds/lone pairs so how is one to know which is which?

Ya Gao
Posts: 52
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 1 time

Re: Tetrahedral vs Trigonal Pyramid

Postby Ya Gao » Sun Nov 12, 2017 5:27 pm

Tetrahedral is when the central atom has only four bonds around it(no lone pairs) and trigonal pyramid is when the central atom has three bonds and one lone pair around it. Hope it helps.

Danah Albaaj 1I
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

Re: Tetrahedral vs Trigonal Pyramid

Postby Danah Albaaj 1I » Sun Nov 12, 2017 5:50 pm

Another way to think of it is trigonal pyramidal is a tetrahedral shape that has lost a bond and replaced it with a lone pair. You can see it when you look at the VSEPR notation for both shapes, tetrahedral is AX4 while trigonal pyramidal is AX3E.


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