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Potassium is a highly reactive metal while argon is an inert gas. Explain this difference based on their electron configurations.
10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following is the correct electron configuration for arsenic (As)?
A
[Ne] 3s2 3p6 3d10 4s2 4p3
B
[Xe] 6s2 4f14 5d10 6p3
C
[Ar] 4s2 3d10 4p3
D
[Kr] 5s2 4d10 5p3
Verified step by step guidance1
Identify the atomic number of arsenic (As), which is 33. This means arsenic has 33 electrons.
Recall the order of filling electron orbitals according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.
Use the noble gas shorthand notation to simplify the electron configuration. The noble gas preceding arsenic is argon (Ar), which has an electron configuration of [Ar] = 1s² 2s² 2p⁶ 3s² 3p⁶.
Continue filling the orbitals after [Ar] with the remaining electrons: 4s², 3d¹⁰, and 4p³. This accounts for the remaining 15 electrons (2 in 4s, 10 in 3d, and 3 in 4p).
Combine the noble gas core with the filled orbitals to write the electron configuration for arsenic: [Ar] 4s² 3d¹⁰ 4p³.
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