MDCAT Chemistry MCQ #961

A student measures ionization energy of elements. Why does ionization energy decrease from nitrogen to oxygen despite increasing nuclear charge?

MDCAT Chemistry MCQ #961

  1. Question 1

    Q1. A student measures ionization energy of elements. Why does ionization energy decrease from nitrogen to oxygen despite increasing nuclear charge?

    • A) Electron repulsion in p-orbital
    • B) Increased shielding
    • C) Smaller atomic radius
    • D) Higher electron density

    Answer: Electron repulsion in p-orbital

    Explanation: Electron-electron repulsion in the half-filled p-orbital makes oxygen's outer electron easier to remove. Nuclear charge increases but is overwhelmed by internal repulsion.