객관식
The chemical reactivity of an element is primarily determined by which of the following?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
Multiple Choice
How many valence electrons does helium (He) have?
A
8
B
2
C
0
D
1
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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.
Recognize that helium's electrons fill the first energy level (1s orbital), which is also its outermost shell.
Conclude that helium has 2 valence electrons because both electrons are in its outermost shell.
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