Page 4 - Redox Reactions

Oxidation number (Oxidation state)

 Oxidation number of an element in a compound is the residual charge on the element when

all the other atoms are removed from it as ions.

 For example oxidation number of Mn in KMnO4 is the residual charge on Mn when one K

+ 2-
atom and four O atoms removed from it as K and O ions respectively.

The chemical bonding method.

The rules are :

1. For one covalent bond assign one unit negative charge to electronegative atom and one unit

positive charge to less electronegative atom e.g. (electronegativity A> B).

2. No charge when the covalent bond is between like atoms.

3. In case of coordinate bond assign two unit negative charge to acceptor atom and two unit

positive charge to donor atom e.g. (electronegativity A > B).

4. No charge when donor in coordinate bond is more electronegative than acceptor eg

(electronegativity A > B).

5. When coordinate bond is between similar atoms assign two unit negative charge to acceptor

and two unit positive charge to donor e.g. (electronegativity same)