Q.What is the two dimensional coordination number of a molecule in square close-packed layer?

In a square close-packed two-dimensional layer, every sphere is in contact with four neighbours (on …

Step 1 – Square close packing geometry.

In a square close-packed layer the spheres are arranged so that each row lies directly above the previous one, forming a square pattern (rows and columns aligned).

Step 2 – Count nearest neighbours.

Take any one sphere. It is touched by its neighbours on the left, right, top and bottom — exactly four spheres in the same plane.

Step 3 – Conclusion. …

Count in-plane nearest neighbours for the square packing arrangement; aligned rows …

• Giving 6 (that is for hexagonal close packing, not square packing).
• Counting diagonal spheres as neighbours; in square packing the diagonal spheres do not touch, so they are not coun …