[peterschmidt3943]

Hello,

I have a few questions regarding the topic oxidation number
What are the oxidation numbers of following molecules?

O₂·− => in my book it says -1/2, but why???
OH·
OH^-
H₂O

IO₃^-
IO₄^-


C2H6 => H=6 C=-6
C2H5Cl
C2H5OF 
C2H4O2

to the last three: I did not know what to write since I have to include the inductive effect, isnt it? How do I identify the oxidation number then?
I need quick help on this one please, it is exam relevant for my medical studies..

[Borek]

What are the oxidation numbers of following molecules?

Oxidation number is a property of an atom, not of a molecule.

[peterschmidt3943]

atom*

[Borek]

What rules do you know? Just apply them, most of these molecules are trivial to analyze.

[peterschmidt3943]

O₂·− =>  -1/2, but why???
OH· => I dont know..
OH^- O= -2  H=2
H₂O  => O=-2  H =2

IO₃^-  O= -5   I = 5
IO₄^-  O=-7  I =7


C2H6 => H=6 C=-6
C2H5Cl   => H=5   Cl=-1   C= -4
C2H5OF  =>  H= 5  O=-2   F=-1  C=-2
C2H4O2  =>  O=0 H=4  C= -4


everything alright ?

[Borek]

Comon error:

H₂O  => O=-2  H =2

You are right about oxygen, but you have TWO hydrogen atoms, not one. Every hydrogen atom has its own oxidation number (as the atoms are equivalent, their oxidation numbers are identical).

[peterschmidt3943]

so, H=1 and O=-2 ?

and what about the rest?

[Borek]

so, H=1 and O=-2 ?

Yes.

and what about the rest?

Try them again, knowing what you did wrong.