Multiple Choice
Which element has a total of five occupied principal energy levels?
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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 for arsenic (As)?
A
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^1
B
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^5
C
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^3
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 arsenic (As), which tells you the total number of electrons in a neutral atom. Arsenic has an atomic number of 33, so it has 33 electrons.
Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, and so on.
Write down the electron configuration by filling orbitals in order until you reach 33 electrons. Remember that each s orbital can hold 2 electrons, each p orbital can hold 6 electrons, and each d orbital can hold 10 electrons.
Check the distribution of electrons in the 4p orbitals, since arsenic is in group 15 and should have 3 electrons in the 4p subshell (4p^3).
Compare the given options with the expected configuration and select the one that matches the correct number of electrons and the correct filling order, especially focusing on the 4p subshell occupancy.
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