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Explaining order of electron shell filling without mentioning s,p,d?

Discussion in 'Science' started by Jim_K, Feb 11, 2011.

  1. Hi,
    I'm going through AQA C3 with my Y11 at the moment, and I got a little stuck the other day. They are supposed to know that transition metals have their properties because of the order that electron shells fill, but they don't need to know about sub-shells.
    I really struggled to explain it without talking about sub-shells and orbitals and suchlike. My group just like to know stuff so I gave them the AS-level version of the story anyway, but I need to make sure they concentrate on the GCSE bit for now.
    So, how does one give a decent explanation without mentioning stuff that they don't need to know just yet?
    Ta...
     
  2. Why are you so terrorised by the specification? It's not a syllabus. Teach your students what you [and they] like... the spec. merely defines the content of the examinations.
    Just be ready for a sensible answer to the question as to why 4s fill before 3d, and then why the order reverses after Scandium but electron density is preserved in the highest occupied AO !
     
  3. My colleagues wouldn't recognise that description of my teaching. I'm not in the least terrified by or bound to specifications - our lessons start with GCSE specs and head rapidly off into the wild blue scientific yonder. The point is that I also try to make it clear to them what their exam in May will or will not ask them about.
    In this case, I couldn't come up with a convincing explanation that would suit their C3 exam. AS, yes, but GCSE, no.
     
  4. Is there a problem teaching this class more than they need to know? You seem keen to separate the knowledge into what they will and will not need for the exam, which leaves me wondering, will your students be marked down for answering a question with AS-level knowledge? Surely the examiner will recognise that the answer is correct and that it merely contains a higher level of detail? I am sorry to hijack your thread, I am half way through my PGCE and really interested in knowing about things like this
     
  5. I just did this lesson. I showed them some electron diagrams of Transition metal and got them to identify the metals, simply by counting electrons. I didn't really touch on sub levels (apart from the top end student who were interested). Explained that once the third energy level had eight electrons, the fourth energy level gained two electrons the pattern skipped back to third energy level for the next ten electrons. I gave them the standard exam question mark scheme which is about all they have to learn! Tricky to teach well without covering much of AS electronic structure.
     
  6. Henriettawasp

    Henriettawasp New commenter

    Sadly, no. The 'examiner' is in reality a marker with a mark scheme. This specifies exactly which answers are allowed and which are not. There will be no room for any deviation from the script. The very brightest students need to know this so they can give just the expected answer.
     
  7. As an experienced GCSE and A level examiner I disagree. A mark scheme 0often contains most if not all correct responses (GCSE mark schemes tend to be as simplistic as possible, matching what is stated in the specs). They are not however rigid documents and the examiner has some leeway; ultimately, if the science is correct then the marks will be awarded.
    For example, a question may ask 'what is electric current?' and the mark scheme may say a 'flow of electrons' but 'the flow of charge' would be also be awarded, even if not stated in the mark scheme. There is no harm in teaching beyond the specs. More often or not mark schemes say more about what not to accept than what is acceptable.
     
  8. Hi Jim,
    I have got a worksheet that I give to my class about general atomic structure, but it can be adapted. Send me your email and I will forward it on, It may be some use.

    Jimbo
     
  9. marshypops

    marshypops New commenter

    Sorry this is not my experience and I mark GCSE level and A-level Chemistry papers, if a student shows that he/ she has understood the question and given a correct answer that is of a higher level than the question paper then they will get the marks <u>unless</u> they include something that is incorrect and cannot be ignored (of course).

     

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