Chapter 29, Problem 15P

To determine

To explain: The reason for considering sodium chloride crystal a good insulator.

Answer to Problem 15P

  $NaCl$ crystal is a good insulator because its shells have tight bond of electrons.

Explanation of Solution

Introduction: An insulator is a material or element that does not allow conducting the electric current. These kinds of materials have very tight electric bonding in their cell.

$Na$ has only 1 electron in the $3s$ shell, while $Cl$ has $5$ electrons in the $2p$ shell. In $NaCl$ , electrons from the $3s$ shell in $Na$ is transferred to the $2p$ shell in $Cl$ , so both shells becomes stabilized. Thus, a large energy is required to unbalance the electron. Hence, $NaCl$ is good insulator.

Conclusion: $NaCl$ crystal has no free electron in its shell that’s why it is a good insulator.