Multiple Choice
Which of the following electron configurations represents an excited state for an atom of calcium?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following is the complete electron configuration for a neutral fluorine atom?
A
1s^2 2s^2 2p^6
B
1s^2 2s^2 2p^3
C
1s^2 2s^2 3p^5
D
1s^2 2s^2 2p^5
Verified step by step guidance1
Determine the atomic number of fluorine, which tells you the number of electrons in a neutral atom. Fluorine has an atomic number of 9, so it has 9 electrons.
Recall the order in which electron orbitals are filled according to the Aufbau principle: 1s, 2s, 2p, 3s, 3p, and so on.
Distribute the 9 electrons into the orbitals starting from the lowest energy level: fill the 1s orbital with 2 electrons, then the 2s orbital with 2 electrons, and place the remaining electrons in the 2p orbital.
Count the electrons in each orbital after filling: 1s has 2 electrons, 2s has 2 electrons, and 2p will have the remaining 5 electrons (since 2 + 2 + 5 = 9).
Write the complete electron configuration by combining the filled orbitals and their electron counts: $1s^{2} 2s^{2} 2p^{5}$.
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