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Unilorin Post-UTME Chemistry 2023 (Model questions) Question 10

Question 10

Atomic Structure

What is the electronic configuration of chloride ion (Cl−)?

  1. A.1s22s22p63s23p5
  2. B.1s22s22p63s23p6
  3. C.1s22s22p63s23p4
  4. D.1s22s22p63s23d103p6
Show the answer and explanation

Answer: B (1s22s22p63s23p6)

Explanation

Chlorine (17 electrons) ends in 3p5; the chloride ion gains one electron, giving 18 electrons ending in 3p6.