Multiple Choice
Which of the following is the correct electron configuration for the element phosphorus (atomic number 15)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following electron configurations would you expect to belong to a reactive nonmetal?
A
1s^2 2s^2 2p^1
B
1s^2 2s^2 2p^6 3s^2
C
1s^2 2s^2 2p^5
D
1s^2 2s^2 2p^6
Verified step by step guidance1
Identify the general characteristics of reactive nonmetals: they typically have nearly full valence shells and tend to gain electrons to achieve a stable octet configuration.
Analyze each electron configuration by determining the number of electrons in the outermost shell (valence shell). For example, in the configuration $1s^2 2s^2 2p^5$, the valence shell is the second shell with 2 electrons in the 2s subshell and 5 electrons in the 2p subshell, totaling 7 valence electrons.
Recall that reactive nonmetals often have 5, 6, or 7 valence electrons, making them eager to gain electrons to complete their octet, unlike noble gases which have full valence shells and are generally unreactive.
Compare the given configurations to see which one has a valence shell with 7 electrons, indicating a high reactivity typical of nonmetals like halogens.
Conclude that the configuration with $1s^2 2s^2 2p^5$ corresponds to a reactive nonmetal because it has 7 valence electrons and is one electron short of a full octet, making it chemically reactive.
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