I don't know how to do this, pls help!

The table lists the lattice energies of some compounds.

Compound
Lattice Energy (kJ/mol)
LiF –1,036
LiCl –853
NaF –923
KF –821
NaCl –786

Which statement about crystal lattice energy is best supported by the information in the table?
The lattice energy increases as cations get smaller, as shown by LiF and KF.
The lattice energy increases as the cations get larger, as shown by LiF and LiCl.
The lattice energy decreases as cations get smaller, as shown by NaCl and NaF.
The lattice energy decreases as the cations get smaller, as shown by NaF and KF.

Respuesta :

Cations from smallest to largest
Li⁺ ,Na⁺, K⁺ (from Periodic Table, the bigger number of period, the bigger size, of atom, so the bigger size of cation)

1) LiF smaller  cation then KF
1,036                                 853
The lattice energy increases as cations get smaller, as shown by LiF and KF.
I think this one should be correct answer, because the compared substances have also the same anion, and we can compare cations in them.

2) The same cation Li , so wrong statement.

3)
The same cation Na , so wrong statement.

4) NaCl smaller cation then KF
  786                                   853

its A ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,