Multiple Choice
How many valence electrons are present in a neutral atom of aluminum (Al)?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
Multiple Choice
How many electrons are present in the outermost energy level (valence shell) of a neutral potassium (K) atom?
A
8
B
7
C
2
D
1
Verified step by step guidance1
Identify the atomic number of potassium (K), which tells you the number of protons and, for a neutral atom, also the number of electrons. Potassium has an atomic number of 19.
Determine the electron configuration of potassium by filling the energy levels in order: 1s, 2s, 2p, 3s, 3p, and then 4s.
Write the electron configuration for potassium: \$1s^2 2s^2 2p^6 3s^2 3p^6 4s^1$.
Recognize that the outermost energy level (valence shell) is the highest principal quantum number (n), which is 4 in this case.
Count the number of electrons in the valence shell (4s orbital), which is 1 electron for potassium.
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