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Multiple Choice
How many valence electrons does an atom of aluminum (Al) have?
A
2
B
4
C
3
D
1
Verified step by step guidance
1
Identify the atomic number of aluminum (Al), which is 13. This tells us the total number of electrons in a neutral atom of aluminum.
Write the electron configuration of aluminum to understand the distribution of electrons in its shells: $1s^2 2s^2 2p^6 3s^2 3p^1$.
Recognize that valence electrons are the electrons in the outermost shell (highest principal quantum number). For aluminum, this is the third shell (n=3).
Count the electrons in the outermost shell: $3s^2$ and $3p^1$ add up to $2 + 1 = 3$ valence electrons.
Conclude that an atom of aluminum has 3 valence electrons based on its electron configuration.