Deducing Oxidation Numbers
- The oxidation numbers of all other atoms in their compounds can vary
- By following the oxidation number rules, the oxidation number of any atom in a compound or ion can be deduced
- The position of an element in the periodic table can act as a guide to the oxidation state
Oxidation Numbers & The Periodic Table
- Test your understanding on the following examples:
Worked example
State the oxidation number of the atoms in blue in these compounds or ions
a) P2O5
b) SO42-
c) H2S
d) Al2Cl6
e) NH3
f) ClO2-
Answers:
Are oxidation numbers always whole numbers?
- The answer is yes and no
- When you try and work out the oxidation of sulfur in the tetrathionate ion S4O62- you get an interesting result!
The oxidation number of sulfur in S4O62- is a fraction
- The fact that the oxidation number comes out to +2.5 does not mean it is possible to get half an oxidation number
- This is only a mathematical consequence of four sulfur atoms sharing +10 oxidation number
- Single atoms can only have an integer oxidation number, because you cannot have half an electron!
