Multiple Choice
Which of the following correctly represents the orbital diagram for arsenic (atomic number 33)?
10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following represents the electron configuration of a ground-state vanadium (V) atom?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^3
B
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^4
C
1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5
D
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^5
Verified step by step guidance1
Identify the atomic number of vanadium (V), which is 23. This means a neutral vanadium atom has 23 electrons to be placed in orbitals according to the Aufbau principle.
Recall the order of orbital filling based on increasing energy: 1s, 2s, 2p, 3s, 3p, 4s, then 3d. Electrons fill lower energy orbitals first before moving to higher energy orbitals.
Fill the orbitals step-by-step with electrons: 1s can hold 2 electrons, 2s holds 2, 2p holds 6, 3s holds 2, 3p holds 6, 4s holds 2, and then place the remaining electrons in 3d orbitals.
Count the electrons after filling up to 4s: 2 (1s) + 2 (2s) + 6 (2p) + 2 (3s) + 6 (3p) + 2 (4s) = 20 electrons. Since vanadium has 23 electrons, place the remaining 3 electrons in the 3d orbitals.
Write the full electron configuration as $1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 4s^{2} 3d^{3}$, which represents the ground-state electron configuration of vanadium.
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