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Periodic Trends: Flashcards

Revise atomic radius, ionization energy, electronegativity, ionic radius and effective nuclear charge.

10 cardsIntermediate

10 cards

  1. Question
    How does atomic radius change across a period and down a group?
    Answer

    Decreases across a period (left to right); increases down a group.

  2. Question
    What is effective nuclear charge?
    Answer

    The net positive charge felt by an outer electron, roughly Zeff≈Z−SZ_\text{eff} \approx Z - S (protons minus inner electrons).

  3. Question
    What is first ionization energy?
    Answer

    The energy needed to remove one electron from each atom in a mole of gaseous atoms.

  4. Question
    How does first ionization energy change across a period and down a group?
    Answer

    Increases across a period; decreases down a group.

  5. Question
    Which element is the most electronegative?
    Answer

    Fluorine (3.98 on the Pauling scale).

  6. Question
    Is a cation larger or smaller than its atom?
    Answer

    Smaller. It often loses a whole shell, and the remaining electrons are pulled in more strongly.

  7. Question
    Is an anion larger or smaller than its atom?
    Answer

    Larger. The added electrons repel each other, and the same nuclear charge holds more electrons.

  8. Question
    Order by size: NaX+\ce{Na+}, FX−\ce{F-}, MgX2+\ce{Mg^2+}, OX2−\ce{O^2-}
    Answer

    OX2−>FX−>NaX+>MgX2+\ce{O^2-} > \ce{F-} > \ce{Na+} > \ce{Mg^2+} (all have 10 electrons; more protons means a smaller ion)

  9. Question
    Why is the first ionization energy of B lower than that of Be?
    Answer

    Boron's outer electron is in a 2p orbital, which is higher in energy than 2s, so it is easier to remove.

  10. Question
    Why is the first ionization energy of O lower than that of N?
    Answer

    Oxygen's fourth 2p electron is paired; repulsion between the paired electrons makes one of them easier to remove.