Chapter U1.20, Problem 1TAI

Interpretation Introduction

Interpretation:

The role of valence electrons to predict the chemical formulas needs to be explained.

Concept introduction:

To form an ionic compound, the participating atoms gain or lose electrons to get the inert gas electronic configuration. The number of electrons gained or removed by participating elements is known as valency. This valency is equal to the number of electrons present in the last orbit.

Answer to Problem 1TAI

Valency of an element helps to predict the formula of the compound.

Explanation of Solution

This can be explained by taking example of two participating atoms namely Lithium and Chlorine. Now, the chemical formula of the compound which is expected from these two participating atom need to be determined.

Looking at the periodic table it can be found that lithium belongs to group 1 with 1 valence electron. So, it will definitely form Li + ion with a valency of 1.

On the other hand, chlorine belongs to halogen family with one valence electron. So it will produce Cl - ion with a valency 1. Thus, the compound will be LiCl (lithium chloride).

Similarly, calcium and chlorine will form CaCl₂ because Ca has + 2 charge and Cl has -1 charge. 2 chlorine atoms combine with 1 calcium atom to form CaCl₂.

According to this barium and chlorine will form BaCl₂ and sodium and bromine will form NaBr.

Conclusion

Thus, valency helps to find out the formula of a compound.