Question

Which has a higher melting point? AlN or MgO, please explain in detail with one. And how do I find out which element is bigger.

Answer 1

Got me....

Explanation:

The scientist interrogates data. From first principles we might predict that aluminum nitride has a higher melting point than magnesium oxide (why? because in the former instance we got the salt of a trication, and a trianion, rather than the salt of a dication, and a dianion, the which necessarily has the LESSER electrostatic interaction)..

But what we do know? We don't know the data. And it is a fact that the aluminum nitride salt is probably something that you CANNOT put in a bottle... The interwebz reports a melting point for `AlN` of `2200` `""^@C`, whereas for magnesium oxide we gots `2852` `""^@C`. This is not the trend I expected, and clearly other factors are involved....I would even suspect the quoted melting point...how do we know that the melting points were taken from kosher samples?

As to the size of the ELEMENT, i.e. the size of the NEUTRAL atom, it is well-known that atomic size decreases across the Period from left to right as we face the Table....and so the aluminum ATOM is smaller than the magnesium atom.. Again, we should consult the data.. And this site lists the ATOMIC (NOT IONIC) radii, of aluminum and magnesium as `125xx10^-12*m` and `150xx10^-12*m`. Are the given measurements consistent with what we have argued this time?