Question

Consider the following compounds: LiCl, NaBr, and RbBr. Answer the following questions based on expected periodic trends:

(a) Which is expected to have the shortest ionic bonds?

(b) Which is expected to have the highest lattice energy?

(c) Which is expected to have the lowest melting point?

Answer 1

a)

Li have smaller size than Na or Rb.

and

Cl is smaller size than Br.

so

the shortest ionic bond have in LiCl.

b) charge of the ions increases, the lattice energy increases.

and

as the size of the ions increases, the lattice energy decreases.

Hence

LiCl have  the highest lattice energy.

c)

LiCl have lowest melting point.