Sapling Number 3

[Natallie K 3B]

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]

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]

But then why is trigonal bipyramidal not an answer?

[Q Scarborough 1b]

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

[Aaina 2D]

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]

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]

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]

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]

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