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Which of the following is the correct method to determine the number of valence electrons in a neutral atom of a main-group element?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
Multiple Choice
Which of the following represents the valence electron configuration for the helium atom?
A
1s^1 2s^1
B
1s^2 2s^2
C
2s^2
D
1s^2
검증된 단계별 안내1
Recall that the valence electron configuration refers to the electrons in the outermost shell of an atom that participate in chemical bonding.
Identify the atomic number of helium, which is 2, meaning it has 2 electrons in total.
Determine the electron configuration by filling the lowest energy orbitals first, following the Aufbau principle.
For helium, both electrons occupy the 1s orbital, so the electron configuration is \$1s^2$.
Compare the given options to this configuration and recognize that \$1s^2$ correctly represents helium's valence electron configuration.
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