The first four ionization energies for element X (not in kJ/mol) are 170, 350, 1800, 2500. The first four ionization energies for element Y are 200, 400, 3500, 5000. Identify elements X and Y. (There may be more than one correct answer)

Am I right if I say element X may be Magnesium and element Y may be Calcium?

Question

The first four ionization energies for element X (not in kJ/mol) are 170, 350, 1800, 2500. The first four ionization energies for element Y are 200, 400, 3500, 5000. Identify elements X and Y. (There may be more than one correct answer)

Am I right if I say element X may be Magnesium and element Y may be Calcium?

anonymous · Answer

well the IE jumps at the removal of a valence electron after the ion is stable
and both of these jump at the removal of their 3rd electron meaning that have to be in group 2

anonymous · Answer

would that be correct?

chmvijay · Answer

yaa that is correct why mg ? why not sr ?

anonymous · Answer

because Mg has less shielding and Sr would have a larger I1

abb0t · Answer

You know, I just took inorganic II last Winter and we kind of went over this stuff and I forgot all of this. Funny, huh?

anonymous · Answer

I would say yes but I need help so it's kinda not funny :)

abb0t · Answer

Ok, well Sr would have a larger l1? What does that mean?

anonymous · Answer

wait no it would have a smaller $\text{I}_1$ -- more shielding, less energy

chmvijay · Answer

thats right

anonymous · Answer

Sr isnt what I'm asking though...would it be correct to say element X may be Mg and element Y may be Ca? @abb0t

abb0t · Answer

If I remember correctly, yes. Shielding increases as you move down the periodic table, due to atomic size.

anonymous · Answer

so I'm right?

abb0t · Answer

Yeah, anything that has 2 valence $e^-$ I would say is correct.

anonymous · Answer

alright, thanks guys! :)

abb0t · Answer

Sr would be a valid answer too. but then your x, would not be Mg, based on the given info. It would be Ca$^{2+}$