Multiple Choice
Which of the following is the correct electron configuration for selenium (atomic number 34)?
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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 a neutral atom of nickel (atomic number 28)?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^9
B
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^8
C
1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2
D
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6
Verified step by step guidance1
Identify the atomic number of nickel, which is 28. This means a neutral nickel atom has 28 electrons to place in orbitals.
Recall the order of orbital filling based on the Aufbau principle: electrons fill orbitals starting from the lowest energy level to higher ones, typically following the sequence 1s, 2s, 2p, 3s, 3p, 4s, then 3d.
Fill the orbitals with electrons according to their maximum capacities: 1s (2 electrons), 2s (2), 2p (6), 3s (2), 3p (6), 4s (2), and then 3d (10). Add electrons until you reach 28 total.
Remember that for transition metals like nickel, the 4s orbital fills before the 3d orbital, so 4s will have 2 electrons before 3d starts filling.
Write the electron configuration by listing the orbitals and their electron counts in order, ensuring the total number of electrons sums to 28.
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