JAMB Chemistry 1997 Question 9

Question 9

Atomic Structure

The electron configurations of two elements with similar chemical properties are represented by

A.1s²2s²2p⁵ and 1s²2s²2p⁴
B.1s²2s²2p⁴ and 1s²2s²2p⁶3s¹
C.1s²2s²2p⁶3s¹ and 1s²2s¹
D.1s²2s²2p⁴ and 1s²2s¹.

Show the answer and explanation

Answer: C (1s²2s²2p⁶3s¹ and 1s²2s¹)

Explanation

Elements with similar properties are in the same group, so they have the same number of outer electrons. Both configurations in C end in s¹ (sodium and lithium, Group 1).