Re: Oxidation Number Rules...



rekuci@xxxxxxxxx wrote:
> 1. Locate common polyanions (CN-, SCN-, etc..)...you know the overall
> charge for these.
> 2. H is +1
> 3. Alkali metals are +1
> 4. Halogens are -1 except in weird polyanions with oxygen, eg periodate
> and HIO6 above, where they can be +7.
> 5. O is usually -2 (-1 in peroxides)
> 6. Now do the transition metals and N, S, C, P etc. These have the
> most possibilities for having different charges. They can usually be
> figured out independently knowing an identified (poly)anion charge.
> 7. Read your freakin textbook??
>
> For K4[Fe(CN)6], first CN is -1 total. K is +1, therefore [Fe(CN)6] is
> -4 and Fe is +2. In CN-, it is clear that C -4 and N +5 works and are
> common valences for these atoms.
>
> Cu2[HIO6], take the HIO6 first - H is +1, O is -2, so if I is +7, HIO6
> is -4, then Cu has to be +2. You can see that if you guessed I is -1,
> HIO6 would be -12 which would require Cu to be +6, and this is not
> possible. Common sense.
Now try with this one :)

NaBH4

.