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need help with writing out chemical formulas! watch

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    i understand that, for instance, you need one lot of Na (valency +) to balance with Cl (1-) to get a net charge of zero, which is very simple.

    But what the heck do i do when i have, for instance, been asked to write out Magnesium Sulphate?, or Ammonium Hydroxide? << these ones are tricky for me because the one of the ions has two letters in it.

    Help me out please, thank you
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    Well, Mg is 2+
    Sulphate, SO4 is 2-

    Ammonium Hydroxide is NH4Cl
    NH3 has no charge, so it gains a hydrogen from acid (or water), becoming NH4+, which bonds with Cl-

    It's basic periodicity
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    (Original post by ilyking)
    i understand that, for instance, you need one lot of Na (valency +) to balance with Cl (1-) to get a net charge of zero, which is very simple.

    But what the heck do i do when i have, for instance, been asked to write out Magnesium Sulphate?, or Ammonium Hydroxide? << these ones are tricky for me because the one of the ions has two letters in it.

    Help me out please, thank you
    As previous post said, Mg has a valency of (2+) whilst sulphate ion SO4has a valency of (2-) therefore formula of Magnesium Sulphate is:
    MgSO4

    Ammonium ion is NH4+, whilst Hydroxide ion is OH- therefore formula of Ammonium Hydroxide is:
    NH4OH (sometimes brackets are often placed around OH)

    These valencies will/should be in your data booklet!
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    (Original post by piszczel)
    Well, Mg is 2+
    Sulphate, SO4 is 2-

    Ammonium Hydroxide is NH4Cl
    NH3 has no charge, so it gains a hydrogen from acid (or water), becoming NH4+, which bonds with Cl-

    It's basic periodicity
    thanks, i get the idea now. i thought SO4 meant that the valency for the ion was 4+, but it was actually -2
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    (Original post by ilyking)
    thanks, i get the idea now. i thought SO4 meant that the valency for the ion was 4+, but it was actually -2
    There are basics that you have to remember, like CN-, OH-, O 2-, H+, NH4+ (note that NH2 isn't -1), SO4 2; the rest of them can be worked out.
    Ask your teacher about periodicity if you're having doubts.
 
 
 
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