Writing Half Equations from Redox Equations

Hi,

I know how to do them, but I'm stuck on a few examples.

Example 1: So for redox reactions like this...
http://postimg.org/image/z2d5eq9en/

The oxidation state of Fe goes from +3 to 0, it has gained electrons, it has been reduced

So Fe ---> Fe3+ + 3e-

I just wanted to confirm that there are no 'small numbers' used in the half equations. So here, Fe2 (as written in the original equation)

A similar thing follows for Aluminium which has been oxidised.

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Example 2: So for redox reactions like this...
http://postimg.org/image/oj90v6yb7/

The oxidation state for Mn goes from +7 to +2

The half equation for it is written as...
MnO4- + 5e- ---> Mn2+
(NOTE, this is the unbalanced version)

What I don't understand is that why is MnO4- written together?
Is it because the overall compound is negatively charged?
Also, in this reaction, oxygen is a spectator ion.

Why is it involved in the half equation?
Previously, I mentioned whether you can have "small numbers" in your half equations. Here we have "4" as the small number. Why can we not have that one Iron as well then? - (Fe2 ---> 2Fe3+ 6e-)

Thanks in adv

Hi,

I know how to do them, but I'm stuck on a few examples.

Example 1: So for redox reactions like this...
http://postimg.org/image/z2d5eq9en/

The oxidation state of Fe goes from +3 to 0, it has gained electrons, it has been reduced

So Fe ---> Fe3+ + 3e-

I just wanted to confirm that there are no 'small numbers' used in the half equations. So here, Fe2 (as written in the original equation)

A similar thing follows for Aluminium which has been oxidised.

-----------------------------------------------------------------------
Example 2: So for redox reactions like this...
http://postimg.org/image/oj90v6yb7/

The oxidation state for Mn goes from +7 to +2

The half equation for it is written as...
MnO4- + 5e- ---> Mn2+
(NOTE, this is the unbalanced version)

What I don't understand is that why is MnO4- written together?
Is it because the overall compound is negatively charged?
Also, in this reaction, oxygen is a spectator ion. Why is it involved in the half equation?
Previously, I mentioned whether you can have "small numbers" in your half equations. Here we have "4" as the small number. Why can we not have that one Iron as well then? - (Fe2 ---> 2Fe3+ 6e-)

Thanks in adv