Question

which set correctly orders the atoms from lowest to highest ionization energy? rb < na < si < s s < na < si < rb rb < na < s < si s < si < na < rb

Explanation:

Step1: Recall ionization energy trends

Ionization energy increases across a period and decreases down a group.

Step2: Analyze the position of elements

Rb is in Group 1 and Period 5. Na is in Group 1 and Period 3. Si is in Group 14 and Period 3. S is in Group 16 and Period 3. Since Rb is below Na in Group 1, Rb has lower ionization energy than Na. Among Na, Si and S in the same period, ionization energy increases from left - to - right, so Na < Si < S.

Answer:

Rb < Na < Si < S