Arrange the following elements in order of increasing electron affinity: Cl, Na, S, P.

• A. Cl < S < P < Na
• B. Na < P < S < Cl
• C. S < P < Na < Cl
• D. P < S < Cl < Na

Answer: (B)

Verified step by step guidance

1. Understand that electron affinity (EA) is the energy change when an atom gains an electron; generally, a higher (more negative) EA means the atom more readily accepts an electron.
2. Recall periodic trends: EA generally increases across a period from left to right and decreases down a group in the periodic table.
3. Identify the positions of the elements: Na is in Group 1 (alkali metals), P and S are in Period 3, Groups 15 and 16 respectively, and Cl is in Period 3, Group 17 (halogens).
4. Based on trends, Na will have the lowest electron affinity because it is an alkali metal, P will have a lower EA than S because S is to the right of P, and Cl will have the highest EA as a halogen.
5. Arrange the elements in order of increasing electron affinity as: Na < P < S < Cl.