which of the following have the highest lattice energy? and Why/

Question

1. Na2P or Na2O
2. BeS or MgO

Answer 1

The lattice energy depends on the size of atoms and the magnitude of the charges on the atoms. The smaller the atomic radius and the greater the charge, the greater the lattice energy..

Are you sure you meant to compare Na2P to Na2O or did you mean Na3P? I’m assuming it’s the latter. In this case the 3+ charge and 3- charge are greater than the 2+ charges on Na2O so Na3P would have greater lattice energy.