Multiple Choice
Which of the following is the correct electron configuration for boron (atomic number 5)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following is the correct electron configuration for potassium (K)?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4p^1
B
1s^2 2s^2 2p^6 3s^2 3p^5 4s^2
C
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1
D
1s^2 2s^2 2p^6 3s^2 3p^6 3d^1
Verified step by step guidance1
Step 1: Identify the atomic number of potassium (K), which is 19. This means potassium has 19 electrons to arrange in its electron configuration.
Step 2: Recall the order of filling electron orbitals based on the Aufbau principle, which is: 1s, 2s, 2p, 3s, 3p, 4s, then 3d.
Step 3: Fill the orbitals in order until you reach 19 electrons: 1s^2 (2 electrons), 2s^2 (2 electrons), 2p^6 (6 electrons), 3s^2 (2 electrons), 3p^6 (6 electrons), which totals 18 electrons so far.
Step 4: The 19th electron goes into the next available orbital, which is 4s, not 3d or 4p, so the last part of the configuration is 4s^1.
Step 5: Combine all parts to write the full electron configuration for potassium as $1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$.
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