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How many valence electrons does a calcium (Ca) atom have?
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9. Electrons in Atoms and the Periodic Table
Valence Electrons of Elements (Simplified)
Multiple Choice
How many valence electrons does a neutral lithium atom (Li) have?
A
3
B
1
C
8
D
2
검증된 단계별 안내1
Identify the atomic number of lithium (Li), which is 3. This means a neutral lithium atom has 3 protons and 3 electrons.
Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom.
Determine the electron configuration of lithium. The first shell (1s) can hold 2 electrons, so the first 2 electrons fill this shell.
The remaining electron goes into the second shell (2s), which is the outermost shell for lithium.
Conclude that lithium has 1 valence electron because there is only one electron in its outermost shell.
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