Multiple Choice
Which element is represented by the electron configuration 1s^2 2s^2 2p^2?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following is the correct electron configuration for helium (He)?
A
1s^2
B
1s^1 2s^1
C
2s^2
D
1s^2 2s^2
Verified step by step guidance1
Recall that helium (He) has an atomic number of 2, which means it has 2 electrons.
Understand that electron configurations describe the distribution of electrons in atomic orbitals, starting from the lowest energy level.
The first energy level (n=1) has only the 1s orbital, which can hold up to 2 electrons.
Since helium has 2 electrons, both will fill the 1s orbital, resulting in the configuration $1s^{2}$.
Review the other options: $1s^{1} 2s^{1}$ and $2s^{2}$ imply electrons in the second energy level, which is incorrect for helium; $1s^{2} 2s^{2}$ suggests 4 electrons, which exceeds helium's electron count.
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