Chapter 21, Problem 27PS

Interpretation Introduction

Interpretation: The option among the following that is not a property of sodium is to be stated.

Concept introduction: Sodium is an alkali metal and belongs to group $\text{1A}$ of the periodic table. It consists of one electron in its outermost shell. Sodium is a metal and tends to lose its valence electron. Thus, it has oxidation number.

Sodium is very reactive and forms compounds with chlorides, oxides and water. Sodium combines with non-metals and there is a transfer of electrons from sodium to non-metals and thus ions are formed where sodium has a positive charge and non-metals are negatively charged. Thus, it generally forms ionic compounds and reacts vigorously to produce compounds with non-metals. The appearance, texture and colour of any element can be determined by looking at the substance.

The reaction of sodium metal with non-metal produces energy which is released in the form of heat or light. Such reactions, in which energy is released in the form of heat and light are referred to as exothermic reactions.

The electrons in metals like $\text{Na}$ are free to move and thus provide conductivity. However, electrons in non-metals like ${\text{Cl}}_{\text{2}}$ are localized and cannot move freely. In salts like $\text{NaCl}$, the ${\text{Na}}^{\text{+}}$ and ${\text{Cl}}^{-}$ ions are tightly bound. $\text{NaCl}$ Conducts electricity when the salt in ions dissociate to conduct electricity.