Chapter 7.3, Problem 21PP

Interpretation Introduction

Interpretation:

Formula for ionic compound formed by aluminum and bromide.

Concept introduction:

Ionic compounds are formed as the result of formation of positive as well as negative ions. Electrons are basically transformed from one atom to other for formation of rare gas electron structure for each ion.

The atom that forms a positive ion will loses electrons to the atom that basically gains electrons for formation of a negative ion.

Answer to Problem 21PP

Formula is $AlB{r}_3$.

Explanation of Solution

Formula for the ionic compounds formed by aluminum and bromide is ${\text{AlBr}}_{\text{3}}$.

The charge on Al ion is +3 and that on Br ion is -1 thus, to from neutral compound, 1 mol of Al ion should react with 3 mol of Br ion.

Chemical equation is represented as follows:

${\text{Al}}^{3+}+3{\text{Cl}}^{-}\to {\text{AlCl}}_3$

Here, 3 electrons from Al are transferred to 3 Cl atoms (1 electron each).

The electronic configuration is represented as follows:

Conclusion

Therefore, $AlB{r}_3$ is the formula which is required.