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    Hey
    Im finding chemistry AS really challenging in general, especially 'shapes of molecules and ions' and how to determine the no. of lone pairs. I was hoping someone might be able to give me some good tips please.
    Much appreciated
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    I didn't do AS level I did Scottish highers, but the way I do it is by looking at the group the element is in because the group number corresponds to the number of electrons in the element's outer shell.
    The element will only have lone pairs if it is in group 5 or above because there can be up to 8 electrons in the outer shell, so when there are 4 or less electrons in the outer shell they don't have to pair up but when there are 5 or more they do have to pair up.
    So for elements in group 5 or above the number of lone pairs can be worked out by taking away 4 from the group number.
    e.g. oxygen is in group 6, so 6-4=2, and oxygen has 2 lone pairs

    I hope that helped a bit! I hope it makes some sense haha
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    Thanks that's clever.
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    (Original post by memeyazoo)
    Hey
    Im finding chemistry AS really challenging in general, especially 'shapes of molecules and ions' and how to determine the no. of lone pairs. I was hoping someone might be able to give me some good tips please.
    Much appreciated
    Here is an interactive test that may help you with simple shapes of molecules

    Here is another resource on shapes of molecules and ions
 
 
 
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