MDCAT Chemistry MCQ #924

Why does the first ionization energy of oxygen deviate from the general period trend?

MDCAT Chemistry MCQ #924

  1. Question 1

    Q1. Why does the first ionization energy of oxygen deviate from the general period trend?

    • A) Higher effective nuclear charge
    • B) Electron-electron repulsion in p-orbitals
    • C) Increased atomic radius
    • D) Penetration effects of d-orbitals

    Answer: Electron-electron repulsion in p-orbitals

    Explanation: Oxygen's paired p-electrons cause repulsion lowering IE (B). Effective nuclear charge (A) increases across the period.