Calculate the net energy change in kilo joules per mole that takes place on formation of MgF ₂ (s) from the elements: 

Mg(s)+F2(g)⟶MgF2(s) 

The following information is needed: 

Heat of sublimation for Mg(s)= 147.7 kJ/mol

Eea for F(g)= −328 kJ/mol

Bond dissociation energy for F2(g)= 158 kJ/mol

Ei1 for Mg(g)= 737.7 kJ/mol

Electrostatic interactions in MgF2(s)= −2957 kJ/mol

Ei2 for Mg(g)= 1450.7 kJ/mol

Express your answer to four significant figures and include the appropriate units.

Ef=???