If the electron configuration of an element is 1s2 2s2 2p5…
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If the electron configuration of an element is 1s2 2s2 2p5, how many unpaired electrons are there?
A. 2
B. 5
C. 1
D. 4
QUICK ANSWER…
C
SOLUTION…
According to Hund's rule one electron must fill each degenerate orbital for each energy level before pairing up.
This means the 1S orbital is completely filled, 2S orbital is also completely filled. For the 2P orbital, there are 3 degenerate sub-orbitals which are singly filled so that 2 electrons will be remaining. The remaining two electrons will pair up two of the three sub-orbitals and the remaining sub-orbital will be unpaired.
Now for the right answer to the above question:
- Option A is incorrect.
- Option B is incorrect.
- C is correct.
- D is not the correct answer.
QUICK TIPS…
You may please note these/this:
- Always remember that each sub-orbital ought to be singly filled before pairing up.
- S orbital has only one sub-orbital.
- P orbital has 3 sub-orbitals.
- Filling up 5 electrons into these 3 sub-orbitals, two will be paired and one will be unpaired.
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/ culled from 2017 JAMB-UTME Chemistry question 18 /
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2023-01-17 9:16:47 pm by QuizTabletIf the electron configuration of an element is 1s2 2s2 2p5, how many unpaired electrons are there?
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