Chapter U1.21, Problem 2E

Interpretation Introduction

Interpretation:

The use of the periodic table to determine the correct formula of an ionic compound needs to be explained.

Concept introduction:

To form an ionic compound the participating atoms gain or lose electrons to attain noble gas electronic configuration.

Answer to Problem 2E

From periodic table, the valency of an ion can be obtained which helps in predicting the formula of the ionic compound.

Explanation of Solution

This can be explained by taking example of two participating atoms namely aluminium and chlorine. Now, the expected chemical formula of the compound formed from these two participating atom needs to be determined.

Looking at the periodic table it can be found that aluminium belongs to group 13 with three valence electrons. So, it will definitely form Al³ + ion with a valency of 3.

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 AlCl₃ (aluminium chloride).

Conclusion

Thus, periodic table helps in finding correct chemical formula of a compound giving information regarding valency of the participating ions.