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# 3rd Energy Level Electron Capacity- GCSE Watch

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1. Ok, so at school I was taught that in the 3rd shell there is capacity for 8 electrons. However, I find it easier to remember that the formula for the nth shell is 2n squared meaning that, if orbitals are included, the actual capacity is 18. Will I get marked down in my GCSE paper if I say there are 18 instead of 8? I guess what I'm really asking here is if I write something that was taught slightly differently to what it actually is, whatever the topic, will I be marked down?
2. Look at a mark scheme.
Ok, so at school I was taught that in the 3rd shell there is capacity for 8 electrons. However, I find it easier to remember that the formula for the nth shell is 2n squared meaning that, if orbitals are included, the actual capacity is 18. Will I get marked down in my GCSE paper if I say there are 18 instead of 8? I guess what I'm really asking here is if I write something that was taught slightly differently to what it actually is, whatever the topic, will I be marked down?
I think that reason it is "8" at GCSE is due to the fact that the 4s orbital fills up before the 3d orbital and since you will only be tested on like the first 20 elements, they say to use 2,8,8,2 or whatever, which would technically be correct. But for say the 25th element, you would have to write 2,8,13,2 and that maybe considered a bit confusing for GCSE level and so they don't really include that. So all in all, just stick to what is being taught, study the mark scheme and thats pretty much it.
4. Thanks a lot, that really helped! 🙂

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Updated: September 22, 2016
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