So Mg has a higher 1st ionization energy than Na. But why does Na have a higher 2nd ionization energy the Mg? Does this occur with any other groups?

So Mg has a higher 1st ionization energy than Na. But why does Na have a higher 2nd ionization energy the Mg? Does this occur with any other groups?

Looking at a periodic table you'll see that Mg has a full orbital the s2 orbital full taking one a way destabilizes it. However Na doesn't have a full s orbital so taking one a way is not that crazy. With that in mind the second ionization of Na is taking away from a noble gas configuration which is so frequing stable, now that takes a lot of energy. However Mg 2 ionization is no big deal because its already not a full orbital.
Let me know if that helps.

So Mg has a higher 1st ionization energy than Na. But why does Na have a higher 2nd ionization energy the Mg? Does this occur with any other groups?

It could be due to electrons on the orbital.Mg has 2 e on on orbital and is pretty stable so I guess it's 1st ionization energy will higher than Na which only has one e on it's orbital and rather to lose that.While when it lose the first one and go to Noble gases configuration then it does not want to lose any more e and therefore will have higher 2nd ionization energy.
Please correct me if this is wrong.

ill put it simply like this:

1st ionization energy:
Mg according to periodic trends is more to the right therefore the ionization energy is higher than Na.

2nd ionization energy:
Now since you took an electron out of each Mg and Na, Na is at Ne and Mg is at Na position (number of electrons wise). So since Na is very stable (it has the same number of electrons as Ne) the 2nd ionization energy of Na is waaaaay higher than the 2nd ionization energy of Mg because Mg can go another round of ionization before it becomes stable and have the same electron configuration as a noble gas...

your explanation made it crystal clear thanks!