Question

ionization energy
2nd group elements
the data table represents the ionization energy for some elements in group 2. it includes be, mg, ca, sr, and ba. consider the data below and your knowledge of subatomic particle interactions.

element sample | ie (kj/mole)
--- | ---
1 | 550
2 | 899
3 | 508
4 | 734
5 | 590

which element sample represents sr?

Explanation:

Ionization energy (IE) decreases down Group 2 of the periodic table because atomic radius increases, weakening the attraction between the nucleus and valence electrons. The Group 2 elements in order (top to bottom) are Be, Mg, Ca, Sr, Ba, so their IE order from highest to lowest is: Be > Mg > Ca > Sr > Ba.
First, sort the given IE values from highest to lowest:
899 (element 2) > 734 (element 4) > 590 (element 5) > 550 (element 1) > 508 (element 3)
Matching to the element order:
899 = Be, 734 = Mg, 590 = Ca, 550 = Sr, 508 = Ba.
Sr corresponds to the 4th highest IE value, which is element 1.

Answer:

element 1