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    (Original post by Mutleybm1996)
    Does anyone have any advice on getting past 52/60? I can't seem to do it -.-


    Posted from TSR Mobile
    get more questions right
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    does anybody have ideas for grade boundaries for AQA ISAs? I got a 32/50 and am trying to get an A
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    (Original post by Mutleybm1996)
    Does anyone have any advice on getting past 52/60? I can't seem to do it -.-


    Posted from TSR Mobile
    if this is for Chem1 - try using the notes on chemrevise (i think thats the name) - and just be able to recite every word
    oh and PPs
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    a mark scheme for a paper I'm doing says that formation of chlorine free radicals is heterolytic bond fission. I swear its homolytic?
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    (Original post by Wiggledinho)
    a mark scheme for a paper I'm doing says that formation of chlorine free radicals is heterolytic bond fission. I swear its homolytic?
    It's homolytic.
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    (Original post by Silver_moon)
    does anybody have ideas for grade boundaries for AQA ISAs? I got a 32/50 and am trying to get an A
    Look at the AQA 2013 GCE grade boundaries, but it really all depends on which ISA you did. Name:  1398506380740.jpg
Views: 220
Size:  32.9 KB

    For an A you needed 45/50 for the 3T ISA
    For an A you needed 38/50 for the 3X ISA

    32/50 would have just given you a C in the 3X ISA

    While 32/50 would have given you a U in the 3T ISA


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    Any threads for edexcel chem unit 1 and 2?
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    (Original post by L'Evil Fish)
    It's homolytic.
    yeah thought so, mark scheme must be wrong.
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    (Original post by Wiggledinho)
    a mark scheme for a paper I'm doing says that formation of chlorine free radicals is heterolytic bond fission. I swear its homolytic?
    what exam board ?
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    (Original post by pinkgorilla)
    what exam board ?
    wasn't an exam board, just some extra questions we got given - astarexams.com
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    Why does Nitrogen have a lone pair of electrons? It has 5 in it's outer shell so surely it can bond 3 times as 5+3=8 so why is there a lone pair in NH3 surely it's bonded three times to the hydrogen's?

    Sorry it's probably really simple


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    When assigning oxidation numbers to NaClO would Na or Cl take priority?

    So O is -2
    Na is +1 and Cl is -1 so which would i use to determine which is +3 or +1?


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    (Original post by Mutleybm1996)
    Why does Nitrogen have a lone pair of electrons? It has 5 in it's outer shell so surely it can bond 3 times as 5+3=8 so why is there a lone pair in NH3 surely it's bonded three times to the hydrogen's?

    Sorry it's probably really simple


    Posted from TSR Mobile
    The nitrogen is bonded to 3 hydrogen atoms. So they share three electrons with the hydrogen, one each; which means that there is still 2 electron left on the nitrogen and that is the lone pair. 3(atoms of nitrogen bonded with hydrogen) + 3(hydrogen atoms bonded to nitrogen)+2(lone pair) = 8
    Hope that made sense.
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    (Original post by Mutleybm1996)
    When assigning oxidation numbers to NaClO would Na or Cl take priority?

    So O is -2
    Na is +1 and Cl is -1 so which would i use to determine which is +3 or +1?


    Posted from TSR Mobile
    I'm not too sure on this one, but wouldn't it be O is -2, Cl +1, and Na +1
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    (Original post by pinkgorilla)
    I'm not too sure on this one, but wouldn't it be O is -2, Cl +1, and Na +1
    Yep
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    (Original post by L'Evil Fish)
    Yep
    Thanks
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    (Original post by pinkgorilla)
    The nitrogen is bonded to 3 hydrogen atoms. So they share three electrons with the hydrogen, one each; which means that there is still 2 electron left on the nitrogen and that is the lone pair. 3(atoms of nitrogen bonded with hydrogen) + 3(hydrogen atoms bonded to nitrogen)+2(lone pair) = 8
    Hope that made sense.
    Oh, i was thinking of it the wrong way round! A stupid mistake, sorry, thank you
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    (Original post by L'Evil Fish)
    Yep
    Annoyingly the only one's we've done is the ones with two of the known oxidation numbers such as O is -2 and H is +1 in the same compound with one unknown and never two unknown so i was just wondering which would take precedence.


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    Just to check: do oxidation numbers only work on empirical formulae? I made the mistake of thinking that the Oxidation number of N was +4 in N(2)H(4) whilst doing a paper today.
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    (Original post by 78Saab)
    Look at the AQA 2013 GCE grade boundaries, but it really all depends on which ISA you did. Name:  1398506380740.jpg
Views: 220
Size:  32.9 KB

    For an A you needed 45/50 for the 3T ISA
    For an A you needed 38/50 for the 3X ISA

    32/50 would have just given you a C in the 3X ISA

    While 32/50 would have given you a U in the 3T ISA


    Posted from TSR Mobile
    Okay thank you!
 
 
 
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