Paradox Creating tension

Oxidation number and Oxidation state

The o.n. of an atom in a molecule or in a polyatom ion is a hypothetical charge the atom would have if the electrons in each bond were located on the more electronegative atom .
→ oxidation state is the oxidation number per atom
→ an unreacted element has o.n. zero
→ a monoatomic ion has o.n. equal to its charge

Rules for assigning o.n
o.n. of one particular element in a covalent compound or ion is determined by taking o.n. of other elements to be fixed . these are summarized below :
Group I (alkali metals) : +1
Group II (alkaline earth metals) : +2
Group III (boron family) : +3
Hydrogen : +1 , -1(in metal hydrides)
Oxygen : -2 , -1(in peroxides) , +2(in OF₂)
Nitrogen : -3(in ammonia and nitrides), varies when in combination with oxygen
Halogens : -1 (when in direct combination with metals) and varies when in combination with oxygen and other halogens ( as in ICl)

this concept is clear..ut sumplaces i cum across fractional o.n.wich is nt possible..how to get the correct value of o.n??

who said frac o.n is impossible ? look at ferric oxide !

Arrey, matlab it is actually impossible, but it had to be made possible in a way (koi aur chaara nahi bachaa hogaa) :P

Kyunki the structure of some compounds, like S₂O₃^2- mein ek S is in 0 n the other is in +4, n in reactions v need to see just "Sulphur", wahaan par ye thodi kahenge ki this particular alpha-sulphur is in 0 n now it is brking off n being further attached with pqr....n this beta-sulphur atom which was in +4 oxidation is losing so many electrons n going to falaana oxid.n state........i mean just imagine!!

Isliye Average O.S. had to be defined, to explain reactions clearly on the basis of elements n not individual atoms..!