Question

Lattice energy of Al2o3 is more than pbO why

Answer 1

Lattice energy U is proportional to Z⁺ Z^- and disproportional to the R₀ ;

Z⁺ = charge of cation

Z^- = charge of anion

R₀ = R₊+R_- where R₊ = radious of cation and R_- is radious of anion.

so higher the charge and lower the radious, higher will be lattice energy.

here anion is common that is oxide anion but the difference is cation one is Al³⁺ and other is Pb²⁺ .

as Al³⁺ has higher charge and lower radious than Pb²⁺ so Al³⁺ contribute more lattice energy and hence Al₂O₃ has more latice energy than PbO.