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How many valence electrons does helium (He) have?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
Multiple Choice
How many valence electrons does beryllium (Be) have?
A
2
B
6
C
8
D
4
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검증된 단계별 안내1
Identify the element in question, which is beryllium (Be).
Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom.
Determine the electron configuration of beryllium. Beryllium has an atomic number of 4, so it has 4 electrons.
Write the electron configuration: 1s\^2 2s\^2. The outermost shell is the second shell (n=2), which contains the 2s\^2 electrons.
Count the electrons in the outermost shell (2s\^2), which gives the number of valence electrons for beryllium.
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