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Which of the following represents the valence electron configuration for a sodium (Na) atom?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
Multiple Choice
How many valence electrons are present in a neutral atom of boron?
A
4
B
2
C
3
D
5
검증된 단계별 안내1
Identify the element in question, which is boron (B).
Determine the atomic number of boron, which is 5, meaning it has 5 electrons in a neutral atom.
Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom.
Write the electron configuration of boron: \$1s^2 2s^2 2p^1$.
Count the electrons in the outermost shell (the second shell): \$2s^2\( and \)2p^1$ add up to 3 valence electrons.
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