Topic Content:
- Definition of Oxidation Number
- Uses of Oxidation Numbers
- Rules for Determining Oxidation Numbers of Compounds and Elements
- Worked Examples
In order to understand the basic principles underlying the IUPAC system of naming (International Union of Pure and Applied Chemistry), a good knowledge of the concept of oxidation numbers to the atoms of the element in a molecule or ion is very essential.
What is Oxidation Number?
Oxidation number can be defined as the charge on an ion or it is the number of electron(s) on the valence shell of an atom or it is the number of electrons required by an atom to acquire a filled electronic structure.
Uses of Oxidation Numbers:
The oxidation number is;
1. Used in the I.U.P.A.C system of naming chemical compounds.
2. Used in classifying elements into a particular group (family) on the periodic table.
3. Used to know which atom is oxidized or reduced in a redox reaction
4. Used in balancing half-cell equations.
Rules for Determining Oxidation Numbers of Compounds and Elements:
1. The Oxidation number of the non-combined element is zero. Example: O2, H2, Mg, Hg, Cu, Ag, etc.
2. Positive oxidation states are assigned to more electropositive elements and negative oxidation states are assigned to more electronegative elements. Example, (Na+ Cl–)
3. In a compound, the sum of the positive oxidation state and negative oxidation state is zero
4. For any ion, the sum of the oxidation numbers is equal to the charge on the ion. Example: Cl– = -1, Fe3+ = +3, etc
5. The oxidation number of hydrogen is +1 except in metal hydride where it is -1. Example: (NaH, Na+1, H-1)
6. The oxidation number of oxygen is -2, except in peroxide where it is -1 e.g. Na2O2.
7. In any Radical, the sum of the oxidation number of all the atoms equals the charge on its ions.
Example 7.5.1:
Find the oxidation number of copper in Cu2O.
Solution:
Oxidation Number of Oxygen is -2 (Rule 6)
You are viewing an excerpt of this Topic. Subscribe Now to get Full Access to ALL this Subject's Topics and Quizzes for this Term!
Click on the button "Subscribe Now" below for Full Access!
Subscribe Now
Note: If you have Already Subscribed and you are seeing this message, it means you are logged out. Please Log In using the Login Button Below to Carry on Studying!
Responses