achieve #3

[Maia V 1L]

Can someone explain why this is a square planar?

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

[Claire_Sabol_2G]

Coordination number refers to the number of atoms/molecules bonded to the central atom. If we look on the VSEPR chart, we see that a square planar shape involves a central atom consisting of two lone pairs and four other atoms bonded to it. Because we do not look at lone pairs here, we can see that square planar molecules must have a coordination number of four. For example, XeF4 has a central atom Xe bounded to four fluorine atoms. Although Xe has two lone pairs, coordination number is only concerned with bound atoms, so it must be equal to four. Hope this helps!

[Nithya Madhu 2L]

Hey,
Basically for coordination number we are only looking the number of bonds to the central atom, not the lone pairs. The shapes that have 4 bonds to the central atom are tetrahedral and square planar. Even though square planar has 2 lone pairs, this does not matter for the coordination number.
Hope that helps!

[105778693]

When dealing with coordination numbers we are looking at number of bonds to the central atom, not including lone pairs. A coordination number of four gets us tetrahedral and square planar geometries.