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How many valence electrons does a neutral arsenic atom (As) have?
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9. Electrons in Atoms and the Periodic Table
Valence Electrons of Elements (Simplified)
Multiple Choice
How many valence electrons are in a neutral chlorine atom (Cl)?
A
5
B
7
C
8
D
17
검증된 단계별 안내1
Identify the atomic number of chlorine (Cl), which tells you the total number of electrons in a neutral atom. Chlorine has an atomic number of 17.
Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom that participate in chemical bonding.
Determine the electron configuration of chlorine to see how electrons are distributed in its shells. The electron configuration for chlorine is \$1s^2 2s^2 2p^6 3s^2 3p^5$.
Focus on the electrons in the highest principal energy level (n=3), which are the valence electrons. For chlorine, these are the electrons in the 3s and 3p orbitals.
Count the electrons in the 3s and 3p orbitals: \$3s^2\( means 2 electrons, and \)3p^5$ means 5 electrons. Add these to find the total number of valence electrons.
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