객관식
How many valence electrons does a potassium (K) atom have?
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Valence Electrons of Elements
객관식
How many valence electrons does helium (He) have?
A
2
B
8
C
1
D
0
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검증된 단계별 안내1
Identify the element in question, which is helium (He).
Recall that valence electrons are the electrons in the outermost shell of an atom.
Determine the electron configuration of helium. Since helium has an atomic number of 2, it has 2 electrons.
Write the electron configuration for helium: \$1s^2$, meaning both electrons are in the first shell, which is also the outermost shell for helium.
Conclude that helium has 2 valence electrons because its only shell (the first shell) is full with 2 electrons.
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