3.2.4 Properties of Period 3 elements and their oxides (A-level Chemistry) Summary Video

[@Milojs7]

I thought covalent character meant the bond was stronger? how come Al2O3 melting point is lower than MgO? Thanks :)

[@DrdeBruinsClassroom]

This has always bugged me too. So, the bit I'm sure of: Yes covalent character means stronger COMPARED TO WHAT IT WOULD BE ACCORDING TO A BORN-HABER CYCLE (see Y13 Thermodynamics) So that just mean that the Born-Haber prediction for Al2O3 would be even lower. And then the bit where I'm guessing: I suspect it's because the 1:1 ratio of MgO means the ions pack together really neatly, whereas the 2:3 in aluminium oxide means the ions are further apart and that reduces the energy needed to separate them. But I have no evidence for that. I'm just extrapolating from what I do know! If you find out, let me know!