Multiple Choice
Which of the following outer electron configurations would you expect to belong to a reactive metal?
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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 valence electrons are present in the ground-state electron configuration of a nitrogen atom?
A
2
B
7
C
5
D
3
Verified step by step guidance1
Identify the atomic number of nitrogen, which is 7. This means a nitrogen atom has 7 electrons in total.
Write the ground-state electron configuration of nitrogen by filling the orbitals in order of increasing energy: 1s, 2s, 2p, etc. For nitrogen, the configuration is $1s^2 2s^2 2p^3$.
Determine which electrons are valence electrons. Valence electrons are those in the outermost shell (highest principal quantum number). For nitrogen, the outermost shell is the second shell (n=2).
Count the electrons in the 2s and 2p orbitals: $2s^2$ means 2 electrons, and $2p^3$ means 3 electrons, so total valence electrons = 2 + 3.
Conclude that the number of valence electrons in nitrogen is the sum of electrons in the 2s and 2p orbitals.
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