Sapling Number 3

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Natallie K 3B
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Sapling Number 3

Postby Natallie K 3B » Tue Dec 01, 2020 3:09 pm

I was confused about this question on sapling

Which geometry or geometries are common for complexes with a coordination number of 4?

square planar

seesaw

tetrahedral

trigonal bipyramidal

It said the answer is tetrahedral and square planar. I understand why it is tetrahedral, but why square planar?

Q Scarborough 1b
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Re: Sapling Number 3

Postby Q Scarborough 1b » Tue Dec 01, 2020 3:12 pm

The coordination number is the number of bonds. Both square planar and tetrahedral have four bonds. This is why is it is both of these. Hope this helps.

Natallie K 3B
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Re: Sapling Number 3

Postby Natallie K 3B » Tue Dec 01, 2020 3:17 pm

But then why is trigonal bipyramidal not an answer?

Q Scarborough 1b
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Re: Sapling Number 3

Postby Q Scarborough 1b » Tue Dec 01, 2020 3:20 pm

Trigonal bipyramidal is associated with the coordination number 5. It has 5 bonds not 4.

Aaina 2D
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Re: Sapling Number 3

Postby Aaina 2D » Tue Dec 01, 2020 3:20 pm

Natallie K 3B wrote:But then why is trigonal bipyramidal not an answer?


This is because there are 5 bonds involved in trigonal bipyramidal. Hope this helps :)

Natallie K 3B
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Re: Sapling Number 3

Postby Natallie K 3B » Tue Dec 01, 2020 3:44 pm

Oh I'm sorry I meant square planar, not trigonal bipyramidal. Since seesaw also has 4 bonding regions, why is this not an answer?

Tessa House 3A
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Re: Sapling Number 3

Postby Tessa House 3A » Tue Dec 01, 2020 3:48 pm

Both tetrahedral and square planar have four bonds, so they are common for complexes with a coordination number of 4. Trigonal bipyramidal geometries have 5 bonds. Seesaw is not correct because although the coordination number is 4, it is not common for coordination complexes with 4 bonds to form this shape. 9C in the textbook says this, but tetrahedral and square planar are the geometries formed when the coordination number is 4.

abby hyman
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Re: Sapling Number 3

Postby abby hyman » Tue Dec 01, 2020 6:50 pm

As the person above said, you would be correct that seesaw geometry has four bonds and thus a coordination number of 4, it is not the most common geometry for molecules with four bonds.

jessicasilverstein1F
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Re: Sapling Number 3

Postby jessicasilverstein1F » Wed Dec 02, 2020 5:34 pm

The coordination number is the number of bonds present. Both square planar and tetrahedral have four bonds.


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