Multiple Choice
Which of the following represents the ground state electron configuration for selenium (Se)?
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10. Periodic Properties of the Elements
The Electron Configuration
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Which of the following represents the correct electron configuration for a nitrogen atom (atomic number 7)?
A
1s^2 2s^2 2p^3
B
1s^2 2s^2 2p^5
C
1s^2 2s^1 2p^4
D
1s^2 2s^2 2p^2
Verified step by step guidance1
Step 1: Identify the atomic number of nitrogen, which is 7. This means a neutral nitrogen atom has 7 electrons to be placed in orbitals according to the Aufbau principle.
Step 2: Recall the order of filling orbitals: first fill the 1s orbital, then the 2s orbital, and then the 2p orbitals. Each orbital can hold a maximum of 2 electrons.
Step 3: Fill the 1s orbital with 2 electrons: $1s^{2}$. Then fill the 2s orbital with 2 electrons: $2s^{2}$. So far, 4 electrons are placed.
Step 4: Place the remaining 3 electrons in the 2p orbitals. Since 2p can hold up to 6 electrons, and nitrogen has 3 electrons left, the configuration is $2p^{3}$.
Step 5: Combine all parts to write the full electron configuration: $1s^{2} 2s^{2} 2p^{3}$. This matches the correct electron configuration for nitrogen.
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