Question

The number of equidistant oppositely charged ions in a sodium chloride crystal is:
A. 8
B. 6
C. 4
D. 2

Answer 1

Hint: Sodium chloride comes under ionic solid composed of sodium cation and chloride anion. All the salts possess crystalline nature. In an ionic solid, the sizes of the cations are very small as compared to the anions.

Complete Step by Step Answer:
Let's understand what the coordination number means. The coordination number defines the number of coordinate bonds formed by the ligands with the centrally placed metal atom in a coordination compound. If we get to know the coordination number, we can easily find out the count of atoms that surround the central metal ion.

Let's come to the question. Here, we have to find out the count of oppositely charged ions that surround each of the cations and cations. And we know that the ratio of coordination numbers in the structure of rock salt (Sodium chloride) is 6:6. Which means, six chloride ions surround each sodium ion. And six sodium ions surround each chloride ion.

Therefore, the number of ions surrounding each cation and anion in a sodium crystal is 6.
Hence, B option is true.

Note: It is to be noted that, in an ionic solid, the charges that ions carry and the ionic arrangement balances each other that results in the neutral nature of the molecule. The melting point of the ionic solids is very high. And in the solid state, an ionic solid behaves as a bad conductor of electricity because of the non-availability of free electrons.