Born Haber Cycle - A lvl Chem

Lord dejavu SG

Hi all. I need some help regarding Bond Haber Cycles. I know all the basic steps like Standard Atomisation of both elements, followed by ie then ea and finally lattice energy.

But, what happens when the compound they give you have unbalance charges? Like Aluminium Oxide (Al_2O_3) or Barium Chloride (BaCl_2) ?

For Aluminium oxide, after the third ionisation energy of Aluminium, there will be 3 electrons for the dissociated Oxygen atom to take in. But Oxygen only need to take in 2 electrons given its charge of 2+. So what happens to the last remaining electron?

Thanks, and correct me if i typed anything wrongly.

UltimaOnline SG

There are a (relative) total of 2 Al atoms donating a total of 6 electrons (to become 2 Al3+ ions) to a (relative) total of 3 O atoms accepting a total of 6 electrons (to become 3 O2- ions).