Multiple Choice
How many valence electrons does boron (B) have?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
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How many valence electrons are present in a neutral atom of magnesium (Mg)?
A
8
B
4
C
6
D
2
Verified step by step guidance1
Identify the atomic number of magnesium (Mg), which is 12. This means a neutral Mg atom has 12 electrons.
Determine the electron configuration of Mg by filling the orbitals in order: 1s, 2s, 2p, 3s, etc.
Write the electron configuration for Mg: \$1s^2 2s^2 2p^6 3s^2$.
Recognize that valence electrons are the electrons in the outermost shell (highest principal quantum number). For Mg, this is the 3rd shell.
Count the electrons in the outermost shell (3s orbital), which gives 2 valence electrons for magnesium.
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