Multiple Choice
What is the total number of outer (valence) electrons present in a molecule of carbon dioxide (CO_2)?
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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 chlorine (Cl)?
A
1
B
5
C
8
D
7
Verified step by step guidance1
Identify the element in question, which is chlorine (Cl).
Determine the atomic number of chlorine, which is 17, meaning it has 17 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 chlorine: \$1s^2 2s^2 2p^6 3s^2 3p^5$.
Count the electrons in the outermost shell (the third shell): \$3s^2\( and \)3p^5\( add up to \)2 + 5 = 7$ valence electrons.
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