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Electron shell configuration watch

1. Hello everyone.

I am studying science for the first time in 24 years and could do with some help.

The first section covers chemistry and I am a bit confused about the way the arrangement of the electron shells are written.

For example I have seen potassium written two ways 2.8.8.1 and 1s2 2s2 2p6 3s2 s3p6 4s1

2. (Original post by psbryan)
Hello everyone.

I am studying science for the first time in 24 years and could do with some help.

The first section covers chemistry and I am a bit confused about the way the arrangement of the electron shells are written.

For example I have seen potassium written two ways 2.8.8.1 and 1s2 2s2 2p6 3s2 s3p6 4s1

2.8.8.1 shows which orbitals the electrons are in: shell 1 has 2 electrons, shell 2 has 8 electrons, etc.

1s2 2s2 2p6 3s2 3p6 4s1 shows which orbitals within the shell the electrons are in.
3. (Original post by alow)
2.8.8.1 shows which orbitals the electrons are in: shell 1 has 2 electrons, shell 2 has 8 electrons, etc.

1s2 2s2 2p6 3s2 3p6 4s1 shows which orbitals within the shell the electrons are in.
Ok, but why does it need to be written that way? If you know the maximum values for each orbital and the order they go in can you write the simplified version? Or is there a more important reason to do so?

Ta.
4. (Original post by psbryan)
Ok, but why does it need to be written that way? If you know the maximum values for each orbital and the order they go in can you write the simplified version? Or is there a more important reason to do so?

Ta.
In practice what you would usually write for potassium is: [Ar]4s1, i.e. K has the electronic configuration of Ar, plus an extra 4s electron.

For valence electrons you should always show which orbitals the electrons are present in, as it's not always as simple as filling up one set then moving onto another.

If you have to do exams, just do whatever they tell you as they may want to test that you know how to write complete electronic configurations.
5. (Original post by alow)
In practice what you would usually write for potassium is: [Ar]4s1, i.e. K has the electronic configuration of Ar, plus an extra 4s electron.

For valence electrons you should always show which orbitals the electrons are present in, as it's not always as simple as filling up one set then moving onto another.

If you have to do exams, just do whatever they tell you as they may want to test that you know how to write complete electronic configurations.
Thanks very much. I think I am starting to get it now, it's only taken 24 years!
6. (Original post by psbryan)
Ok, but why does it need to be written that way? If you know the maximum values for each orbital and the order they go in can you write the simplified version? Or is there a more important reason to do so?

Ta.
The breakdown into orbitals has significance with regards to how atoms can bond, and other properties. It depends what level you're working to as to whether you need to understand the implications of that, but if it's just being able to write it that way then you should probably just make a habit of it. It's no harder really, just a little more to memorise. I suspect you won't need to go beyond calcium anyway, am I correct?
7. You are spot on. I am doing the online equivalent of a double science GCSE with the possibility of then doing a science access course before studying nutrition.

I know that I am probably delving further into things than I need to at the moment but if I don't fully understand something or have too many unanswered questions or things just don't make sense then I have trouble learning. It also helps that I am enjoying this subject far more than I ever expected!
8. (Original post by psbryan)
You are spot on. I am doing the online equivalent of a double science GCSE with the possibility of then doing a science access course before studying nutrition.

I know that I am probably delving further into things than I need to at the moment but if I don't fully understand something or have too many unanswered questions or things just don't make sense then I have trouble learning. It also helps that I am enjoying this subject far more than I ever expected!
That's good

Problem is, with electronic structure, when you go deeper, you need to do a lot more background into physics and quantum mechanics to properly understand what's going on. It's time consuming, and many find it conceptually difficult.

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Updated: February 3, 2017
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