MDCAT Chemistry MCQ #939

What causes the lanthanide contraction but not the actinide contraction?

MDCAT Chemistry MCQ #939

  1. Question 1

    Q1. What causes the lanthanide contraction but not the actinide contraction?

    • A) Greater shielding in 4f orbitals
    • B) Poorer shielding by 5f electrons
    • C) Stronger effective nuclear charge in lanthanides
    • D) Lower ionization energy in actinides

    Answer: Poorer shielding by 5f electrons

    Explanation: 5f electrons shield poorly (B), causing less contraction in actinides compared to 4f in lanthanides.