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Electron Configuration: Flashcards

Revise subshell capacities, filling order, Hund's rule and configurations of atoms and ions.

10 cardsIntermediate

10 cards

  1. Question
    How many electrons can s, p, d and f subshells hold?
    Answer

    s 2, p 6, d 10, f 14

  2. Question
    How many electrons can one orbital hold?
    Answer

    Two, with opposite spins (Pauli exclusion principle).

  3. Question
    Which fills first: 4s or 3d?
    Answer

    4s fills before 3d.

  4. Question
    What is Hund's rule?
    Answer

    Electrons occupy separate orbitals in a subshell, with parallel spins, before pairing up.

  5. Question
    Write the electron configuration of oxygen (Z = 8).
    Answer

    1s2 2s2 2p41s^2\, 2s^2\, 2p^4

  6. Question
    Write the noble-gas configuration of sodium (Z = 11).
    Answer

    [Ne] 3s¹

  7. Question
    Write the configuration of FeX2+\ce{Fe^2+} (Fe: Z = 26).
    Answer

    [Ar] 3d⁶ (the two 4s electrons are removed first)

  8. Question
    What are the electron configurations of chromium and copper?
    Answer

    Cr: [Ar] 3d⁵ 4s¹; Cu: [Ar] 3d¹⁰ 4s¹ (exceptions to the simple filling order).

  9. Question
    How many unpaired electrons does nitrogen have?
    Answer

    Three: its 2p³ electrons occupy three separate orbitals.

  10. Question
    What does the noble-gas core [Ar] represent?
    Answer

    The 18 electrons of argon: 1s2 2s2 2p6 3s2 3p61s^2\, 2s^2\, 2p^6\, 3s^2\, 3p^6