Multiple Choice
Which of the following is the correct electron configuration for a neutral lithium (Li) atom?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which change to the electron configuration of nitrogen (atomic number 7) would result in a stable, noble gas configuration?
A
Lose one electron to achieve the configuration 1s^2 2s^2 2p^2
B
Lose three electrons to achieve the configuration 1s^2 2s^2 2p^0
C
Gain one electron to achieve the configuration 1s^2 2s^2 2p^4
D
Gain three electrons to achieve the configuration 1s^2 2s^2 2p^6
Verified step by step guidance1
Step 1: Write the ground-state electron configuration of nitrogen (atomic number 7). Nitrogen has 7 electrons, so its configuration is $1s^2 2s^2 2p^3$.
Step 2: Understand that a stable, noble gas configuration means having a completely filled valence shell, which for the second period corresponds to the electron configuration of neon: $1s^2 2s^2 2p^6$.
Step 3: Analyze each proposed change to see if it leads to the noble gas configuration. Losing electrons reduces the number of valence electrons, so losing one or three electrons will not fill the 2p subshell.
Step 4: Consider gaining electrons. Adding one electron to nitrogen's $2p^3$ configuration results in $2p^4$, which is not a full shell. Gaining three electrons fills the $2p$ subshell to $2p^6$, matching neon's configuration.
Step 5: Conclude that gaining three electrons to achieve $1s^2 2s^2 2p^6$ results in a stable, noble gas configuration, which is the correct change for nitrogen.
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