10
QuizMultiple Choice

Atomic Numbers and Electron Configurations

Question 10 • *26-27 CFISD TX-Chemistry A CR

Which is the electron configuration for boron?

Answer
A
1s22s3
B
1s22s23s1
C
1s12s22p2
D
1s22s22p1

Explanation

Boron has 5 electrons. Fill the orbitals in order: 1s holds 2 electrons, 2s holds 2, and the remaining 1 goes into 2p. This gives 1s² 2s² 2p¹, choice D.

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