Multiple Choice
The diagram below shows an orbital with a dumbbell shape oriented along the x-axis. Which type of orbital is represented?A) 1sB) 2p_xC) 3d_{z^2}D) 2p_z
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following represents the ground state electron configuration of a selenium (Se) atom?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6 4p^4
B
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^2
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^6
Verified step by step guidance1
Identify the atomic number of selenium (Se), which is 34. This means a neutral selenium atom has 34 electrons to be placed in orbitals according to the Aufbau principle.
Recall the order of orbital filling based on increasing energy levels: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on.
Fill the orbitals step-by-step with electrons, respecting the maximum number of electrons each orbital can hold: s orbitals hold 2, p orbitals hold 6, and d orbitals hold 10 electrons.
Check the given configurations and verify if the total number of electrons adds up to 34 and if the distribution follows the correct filling order and Hund's rule (maximizing unpaired electrons in degenerate orbitals).
Confirm that the correct ground state configuration for selenium ends with 4p^4, since selenium has 6 electrons beyond the argon core (which ends at 3p^6), filling 4s^2, 3d^{10}, and then 4p^4.
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