Question

1. based on their positions in the periodic table, predict which has the smallest first ionization energy: li, cs, n, f, i

Explanation:

Step1: Recall ionization energy trend

First ionization energy generally increases across a period (left to right) and decreases down a group (top to bottom) in the periodic table.

Step2: Analyze positions of elements

• Li (lithium) and Cs (cesium) are in Group 1 (alkali metals). Cs is below Li in the group.
• N (nitrogen), F (fluorine) are in Period 2, Group 15 and 17 respectively. I (iodine) is in Group 17, below F.
• For Group 1, as we go down (Li → Cs), ionization energy decreases. Among N, F, I, F has higher ionization energy than N (across period) and I (down group).
• Comparing Cs (Group 1, lower position) with others: Cs is lower in the group than Li, and in lower groups than N, F, I. So Cs will have the smallest first ionization energy.

Answer:

Cs (Cesium)