Compound	Ions	L.E. (kJ/mol)
LiCl	Li+1    Cl-1	845
NaCl	Na+1   Cl-1	787
KCl	K+1     Cl-1	709
LiF	Li+1     F-1	1033
CaCl2	Ca+2    Cl-1	2258
AlCl3	Al+3     Cl-1	5492
CaO	Ca+2    O-2	3401
Al2O3	Al+3     O-2	15916

Lattice energy depends on two factors:

1. Ion Size
        Small ions are close to each other and exhibit stronger attraction.
      When charges are same, smaller ions have higher L.E.
 
    LiCl  versus  NaCl
        The charges are the same (+1 & -1)
       Since Li⁺¹ is smaller than Na⁺¹,  LiCl has greater L.E.
 

2. Ion Charge
        Ion with higher charges exhibit stronger attraction.
      When size is similiar, higher charges lead to higher L.E.
 
      KCl  versus  CaCl₂
        K⁺¹ and Ca⁺² are similiar in size (same period next to each other).
      Since Ca⁺² has higher charge, CaCl₂ has greater L.E.