Multiple Choice
Which electron configuration represents a violation of the Pauli exclusion principle?
10. Periodic Properties of the Elements
The Electron Configuration
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Potassium has an atomic number of 19. What is its electron configuration?
A
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
B
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹
C
1s² 2s² 2p⁶ 3s² 3p⁶ 4p¹
D
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹ 4s¹
Verified step by step guidance1
Identify the atomic number of potassium, which is 19. This indicates the number of electrons in a neutral potassium atom.
Recall the order of filling electron orbitals based on the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, etc.
Start filling the orbitals with electrons, beginning with the lowest energy level: 1s², then 2s², followed by 2p⁶, 3s², and 3p⁶.
After filling the 3p orbital, the next orbital to fill is 4s, which can hold 2 electrons. However, since potassium has 19 electrons, only 1 electron will go into the 4s orbital, making it 4s¹.
Verify the electron configuration by counting the total number of electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹, which sums up to 19 electrons, matching the atomic number of potassium.
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