MDCAT Chemistry MCQ #783

Why is the first ionization energy of phosphorus higher than sulfur?

MDCAT Chemistry MCQ #783

  1. Question 1

    Q1. Why is the first ionization energy of phosphorus higher than sulfur?

    • A) Phosphorus has a smaller atomic radius
    • B) Sulfur has a higher nuclear charge
    • C) Phosphorus has a half-filled p-orbital
    • D) Sulfur has greater electron shielding

    Answer: Phosphorus has a half-filled p-orbital

    Explanation: Phosphorus's half-filled p-orbital (option C) is unusually stable. Smaller radius (option A) alone doesn't explain the anomaly.