Arrange the following substances in order of decreasing magnitude of lattice energy.

cao, naf, sro, kcl

CaO > SrO > NaF > KCl  

Explanation:

The lattice dissociation energy (LE) is the energy needed to convert 1 mol of the solid crystal into gaseous ions.

A simplified formula for lattice energy is

where q₁ and q₂ are the ionic charges, r is the interionic distance, and κ is a constant.

Thus, lattice energies increase as the

The compounds written in their ionic forms are

Ca²⁺O²⁻, Na⁺F⁻, Sr²⁺O²⁻, and K⁺Cl⁻

We can separate them into two groups:

 (1,1) = NaF and KCl

(2,2) = CaO and SrO

The (1,1) compounds have smaller lattice energies than their (2,2) counterparts.

K⁺ and Cl⁻ are larger ions than Na⁺ and F⁻, so the lattice energy of KCl is less than that of NaF.

Sr²⁺ is a larger cation than Ca²⁺, so the lattice energy of SrO is less than that of CaO.

The order of lattice energies is

CaO > SrO > NaF > KCl