Flashcards in Oxidation Number Rules Deck (11):
1
Free (uncombined) elements
Free (uncombined) elements have an oxidation number of zero
This includes polyatomic elements
2
Monatomic ions
Monatomic ions:
Oxidation number = charge of ion
3
Oxygen
Oxygen:
Usually -2
Exceptions:
Hydrogen peroxide: H2O2 (-1)
Peroxide ion: O22- (-1)
4
Hydrogen
Hydrogen:
Oxidation = +1
Except when bound to metals in binary compounds (-1)
5
Group 1A
Group 1A:
+1
6
Group 2A
Group 2A:
+2
7
Al (Group 3A)
Al (Group 3A):
+3
8
F (Group 7A)
F (Group 7A):
-1
9
Molecular formula or formula unit
Molecular formula or formula unit:
Oxidation number sum must equal zero
10
Polyatomic ions
Polyatomic ions:
Sum of oxidation numbers must = ion charge
11
Oxidation numbers
Can be integers or fractions
E.g. one O in O2- = -1/2