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Chemistry: Atomic Structure & Periodicity Flashcards

7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which electron configuration represents a ground-state chromium atom (Z=24)?

    Answer: [Ar]4s^1 3d^5

    Chromium adopts [Ar]4s^1 3d^5 because a half-filled d subshell adds stability.

  2. The electron configuration of the Fe2+ ion (Fe is Z=26) is:

    Answer: [Ar]3d^6

    Fe loses its two 4s electrons first, giving Fe2+ a [Ar]3d^6 configuration.

  3. Which element is a ground-state aufbau exception due to a fully filled d subshell?

    Answer: Copper

    Copper is [Ar]4s^1 3d^10, gaining stability from a completely filled d subshell.

  4. How many valence electrons does a ground-state selenium atom (Z=34) have?

    Answer: 6

    Selenium is in group 16, so it has 6 valence electrons (4s^2 4p^4).

  5. The noble-gas shorthand for a ground-state bromine atom (Z=35) is:

    Answer: [Ar]4s^2 3d^10 4p^5

    Bromine fills 4s, 3d, and 4p to give [Ar]4s^2 3d^10 4p^5.

  6. Which ion has a noble-gas electron configuration?

    Answer: Ca2+

    Ca2+ has 18 electrons, matching the argon configuration.

  7. A paramagnetic atom must have:

    Answer: At least one unpaired electron

    Paramagnetism arises from one or more unpaired electrons that respond to a magnetic field.