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How many valence electrons does a phosphorus (P) atom have?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
Multiple Choice
How many valence electrons does the element lithium (Li) have?
A
1
B
2
C
4
D
3
검증된 단계별 안내1
Identify the atomic number of lithium (Li), which is 3. This means lithium has 3 electrons in total.
Recall that valence electrons are the electrons in the outermost shell (energy level) of an atom.
Determine the electron configuration of lithium: the first 2 electrons fill the 1s orbital, and the 3rd electron goes into the 2s orbital.
Since the 2s orbital is the outermost shell for lithium, the number of valence electrons is the number of electrons in this shell.
Conclude that lithium has 1 valence electron because only one electron is in its outermost shell.
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