# Oxidation number

1. Apr 16, 2005

### apchemstudent

nevermind i found the answer. However, i just want to know, is hydrogen always assigned the oxidation number of 1+? As well, how come having a negative oxidation number means nitrogen is a strong oxidizer? Or is this wrong? Can someone please explain this to me? Thanks.

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2. Apr 16, 2005

### GCT

hydrogen can also possess -1 states, as in some hydrides. Oxidation number are assigned to the more electronegative atom, oxygen is almost always assigned -2 , recall your definition of oxidizing and reducing agent (oxidizing agent is reduced, gains electrons, acquires a negative charge). Nitrogen in this case is assigned the negative oxidiation number.

3. Apr 16, 2005

### ShawnD

The exact opposite is true. Nitrogen is sort of in the middle in terms of electronegativity, so it generally likes to be neutral. If you make it partially negative, such as ammonia (NH3), you get a weak base and a weak nucleophile. If you make it truly negative, such as sodium amide (NaNH2), you get an unbelievably strong base and strong nucleophile.

You get strong oxidizers by making nitrogen positive such as potassium nitrate (KNO3) or nitrogen dioxide (NO2). Same goes for any other salt where one element becomes slightly positive due to oxygen surrounding it. Examples: H2SO4, KClO3, KClO4, K2Cr2O7, KMnO4.

Assign oxidation numbers by comparing electronegativity. For organic stuff, hydrogen is pretty much always +1. For inorganic stuff, mostly with column 1 metals, hydrogen is -1.

4. Apr 16, 2005

### dextercioby

And 0 in the Hydrogen molecule...

Daniel.

5. Apr 16, 2005

### GCT

Shawn, he/she meant the formal definition of oxidation number, what you're referring to is formal charge

# unshared electrons +.5shared electrons

oxidation number of nitrogen in N2H4

neutral, $$0=2(ON)_n + 4(ON)_h$$ negative oxidation number goes to the more electronegative element, thus the oxidation number of nitrogen is -2.

6. Apr 16, 2005

### Gokul43201

Staff Emeritus
This is wrong. If at all there is a connection, it would imply that "nitrogen" wants to get oxidized and hence is a reducer.

Two points :

(a) Nitrogen, as the molecule N2, is reasonably unreactive and will hardly be called a "strong oxidizer";

(b) If you are refering to some nitrogenous compound, then you must specify the compound. Many nitrogenous componds are oxidizers (though very few are strong), but some are not. NO2 is an oxidizer while N2O is not.

7. Apr 16, 2005

### apchemstudent

Alright, thanks everyone.

8. Apr 16, 2005

### GCT

Yeah, the question was rather poorly worded and vague to say the least, I think that he/she associated "oxidizer" with "high electronegativity" pertaining to the atomic scale. It doesn't make sense to label a molecular compound as "oxidizers" based on the composition of its elements unless it has a common role of doing so, such as KMnO4, also note that she/he was referring to nitrogen, nitrogen by itself, not compounds of nitrogen.

9. Apr 17, 2005

### The Bob

Did you conclude that nitrogen had an oxidation state of -2 then???

The Bob (2004 ©)

10. Apr 17, 2005

### dextercioby

Yes,of course.It would have had -3,if the molecule had been ammonia,but,since it's a N-N simple bond,too,the ON grows by a unit (cf.peroxydic compounds).

Daniel.

11. Apr 19, 2005

### The Bob

Good then.

The Bob (2004 ©)

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