Multiple Choice
How many unpaired electrons are present in the ground state phosphorus (P) 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
Which of the following represents the valence electron configuration for a gallium (Ga) atom?
A
4s^2 4p^3
B
4s^2 4p^1
C
3d^10 4s^2 4p^1
D
4s^2 3d^10
Verified step by step guidance1
Identify the atomic number of gallium (Ga), which is 31. This tells us the total number of electrons in a neutral Ga atom.
Recall that the electron configuration is built by filling orbitals in order of increasing energy, following the Aufbau principle, Hund's rule, and the Pauli exclusion principle.
Write the full electron configuration for Ga by filling orbitals up to 31 electrons: starting from 1s, 2s, 2p, 3s, 3p, then 4s, 3d, and finally 4p orbitals.
Determine the valence electrons by identifying the electrons in the outermost shell (highest principal quantum number, n). For Ga, these are the electrons in the 4s and 4p orbitals.
Express the valence electron configuration by including the electrons in the 4s and 4p orbitals, and if relevant, the filled 3d subshell since it is part of the third shell but often considered part of the core for main group elements.
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