Question

which element has the largest atomic radius in each pair? 1. lithium or cesium? 2. aluminum or phosphorus? 3. calcium or radium? 4. carbon or nitrogen?

Explanation:

Step1: Recall atomic - radius trend

Atomic radius increases down a group and decreases across a period.

Step2: Compare Lithium and Cesium

Lithium (Li) is in period 2 and group 1, Cesium (Cs) is in period 6 and group 1. Since atomic radius increases down a group, Cs has a larger atomic radius.

Step3: Compare Aluminum and Phosphorus

Aluminum (Al) is in group 13 and period 3, Phosphorus (P) is in group 15 and period 3. Since atomic radius decreases across a period, Al has a larger atomic radius.

Step4: Compare Calcium and Radium

Calcium (Ca) is in period 4 and group 2, Radium (Ra) is in period 7 and group 2. Since atomic radius increases down a group, Ra has a larger atomic radius.

Step5: Compare Carbon and Nitrogen

Carbon (C) is in group 14 and period 2, Nitrogen (N) is in group 15 and period 2. Since atomic radius decreases across a period, C has a larger atomic radius.

Answer:

1. Cesium
2. Aluminum
3. Radium
4. Carbon