Question

Rank the following ionic compounds, which have the same crystal structure, from least negative to most negative lattice energy: CsCl, CsBr, and CsI. Please explain.

a) CsCl < CsBr < CsI; increasing ionic radius leads to lower lattice energy
b) CsI < CsBr < CsCl; increasing ionic radius leads to higher lattice energy
c) CsCl < CsI < CsBr; increasing atomic mass leads to lower lattice energy
d) CsBr < CsCl < CsI; increasing atomic mass leads to higher lattice energy

Answer 1

The ranking of the ionic compounds from least negative to most negative lattice energy is CsCl < CsBr < CsI. Increasing ionic radius leads to lower lattice energy.

Step-by-step explanation:

When ranking ionic compounds with the same crystal structure, the lattice energy can be determined by considering the ionic charges and the internuclear distance. In this case, CsCl, CsBr, and CsI have the same crystal structure, but CsBr and CsI have larger ionic radii compared to CsCl. As lattice energy is inversely proportional to the internuclear distance, increasing the ionic radius leads to lower lattice energy. Therefore, the correct ranking is CsCl < CsBr < CsI.