Multiple Choice
What is the total number of electrons required to completely fill the fourth main energy level (n = 4) of an atom?
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10. Periodic Properties of the Elements
Valence Electrons of Elements
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
How many electrons are present in the n = 3 shell of a neutral vanadium (V) atom?
A
11
B
8
C
3
D
5
Verified step by step guidance1
Identify the atomic number of vanadium (V), which tells you the total number of electrons in a neutral atom. Vanadium has an atomic number of 23, so it has 23 electrons.
Recall that the principal quantum number n = 3 corresponds to the third electron shell, which includes the 3s, 3p, and 3d subshells.
Determine the electron configuration of vanadium to see how electrons are distributed among the shells and subshells. The electron configuration is written by filling orbitals in order of increasing energy: 1s, 2s, 2p, 3s, 3p, 4s, and 3d.
Write the electron configuration for vanadium: $1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^6\ 4s^2\ 3d^3$. Note that the 3rd shell includes 3s, 3p, and 3d orbitals.
Count the electrons in the n = 3 shell by adding the electrons in 3s, 3p, and 3d orbitals: $3s^2 + 3p^6 + 3d^3 = 2 + 6 + 3 = 11$ electrons.
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