RULE’S TO FIND OUT OXIDATION NUMBER

by • 27/08/2013 • GeneralComments (0)386

OXIDATION NUMBER:

The charge appears on any atom while present in a molecule is called oxidation number. E.g.

NaCl ————> Na+ + Cl-

 

(Oxidation number of Na in NaCl = +1)

(Oxidation number of Cl in NaCl = -1)

RULE’S TO FIND OUT OXIDATION NUMBER:

i. Infree statethe number of all atom must be equal to zero e.g. Sº , Cº , Pº

ii. The summation of Oxidation Number of all atoms present in a molecule is always zero.

iii. In any molecule the atom with greater electronegativity assigned -ve sign while the atom w     ith lesser electronegativity assigned +ve sign e.g. H+Cl- b/c the electronegativity of Chlorine is greater than Hydrogen.

iv. The oxidation number of oxygen in most of the compounds is -2.

v. The oxidation number of hydrogen attached with metals is -1.

The oxidation number of hydrogen attached with non-metals is +l.

vi. The oxidation number of halogens (F, Cl, Bri, I etc) is -1.

vii. The oxidation number of elements ofGroupIA(Li, Na. K etc) is +1.

The oxidation number of elements of Group IIA (Be, Mg, Ca etc) is +2I

The oxidation number of elements of Group IIIA (B, Al etc) is +3

viii. In polyatomic ion the summation of oxidation number of all atoms is equal to the charge on that molecules for e.g. SO4-2.

Even when you have dig this no motive to be false, it is a very hard thing to!
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