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How many valence electrons does calcium (Ca) have?
A
4
B
2
C
8
D
6
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1
Identify the element in question, which is calcium (Ca).
Determine the atomic number of calcium, which is 20, meaning it has 20 electrons in total.
Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom.
Write the electron configuration of calcium: \$1s^2 2s^2 2p^6 3s^2 3p^6 4s^2$.
From the electron configuration, observe that the outermost shell is the 4th shell (4s), which contains 2 electrons, so calcium has 2 valence electrons.