Just one sec...
 You are Here: Home

# 3rd Energy Level Electron Capacity- GCSE

Announcements Posted on
Take our short survey, £100 of Amazon vouchers to be won! 23-09-2016
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! 🙂

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: September 22, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Justine Greening Q&A

Exam reform and more; post a question for the education secretary