Multiple Choice
Which of the following represents the correct electron configuration for the Ba^{2+} ion?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following represents the correct electron configuration for the Se^{2-} ion?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^2
B
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6
C
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^4
D
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5
Verified step by step guidance1
Identify the atomic number of selenium (Se), which is 34. This means a neutral selenium atom has 34 electrons.
Determine the electron configuration of neutral selenium by filling orbitals in order of increasing energy: 1s, 2s, 2p, 3s, 3p, 4s, 3d, and 4p until all 34 electrons are placed.
Since the ion is Se^{2-}, it has gained 2 extra electrons compared to the neutral atom, increasing the total number of electrons to 36.
Add the 2 extra electrons to the next available orbitals following the Aufbau principle, which will be in the 4p subshell after filling 4s and 3d orbitals.
Write the full electron configuration for Se^{2-} by including all electrons up to 36, ensuring the 4p subshell has 6 electrons to reflect the 2 extra electrons added to the neutral selenium configuration.
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