Question

What is the coordination number of the carbon atoms in the graphite potassium structure, C8K?

(a) 6

(b) 3

(c) 8

(d) 12

I got this question in unit test.

I need to ask this question from Modification of Existing Structures by Ion Exchange and Intercalation Reactions in chapter Preparative Methods of Solid State Chemistry

Answer 1

The correct answer is (d) 12

Explanation: Coordination number is also known as ligancy. It is defined as the number of atoms, ions, or molecules that has a central atom or ion holds as its nearest neighbours in a complex or coordination compound or in a crystal. In potassium graphite structure, the carbon layers are arranged in AAAA pattern where the potassium ions are sandwiched between the pairs of carbon rings, thus resulting as a coordination number 12 of carbon atoms.