Question

which element has the largest atomic radius in each pair? 1. lithium or potassium? 2. sulfur or phosphorus? 3. calcium or beryllium? 4. carbon or fluorine?

Explanation:

Step1: Recall atomic - radius trend

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

Step2: Compare Lithium and Potassium

Lithium (Li) is in period 2 and group 1, Potassium (K) is in period 4 and group 1. Since atomic radius increases down a group, Potassium has a larger atomic radius.

Step3: Compare Sulfur and Phosphorus

Sulfur (S) is in period 3, group 16 and Phosphorus (P) is in period 3, group 15. Since atomic radius decreases across a period, Phosphorus has a larger atomic radius.

Step4: Compare Calcium and Beryllium

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

Step5: Compare Carbon and Fluorine

Carbon (C) is in period 2, group 14 and Fluorine (F) is in period 2, group 17. Since atomic radius decreases across a period, Carbon has a larger atomic radius.

Answer:

1. Potassium
2. Phosphorus
3. Calcium
4. Carbon