Core
Reactions: Redox
Slide 14 of 42
Oxidation state
assignments rules
5. Some elements have fixed oxidation states in all or most of
their compounds and using these oxidation state of other atoms in a
compound (whether ionic or covalent) can be determined. And they
are:
Metals Non-metals
Group
IA metals +1 hydrogen +1
(exception: metal hydrides in which it is -1)
Group
IIA metals +2 fluorine -1
other
halogens (Cl, Br, I) -1 (exception: with
oxygen and other
halogens)
–Aluminum +3
oxygen -2 (exception:
peroxides in which it is -1,
superoxides and with fluorine)
superoxides and with fluorine)
Peroxides are compounds containing two oxygen atoms that have a
single bond between them.
–All
binary peroxides contain O2 in their formula.
Apart from the elements listed above, the rest can be assumed
to have variable oxidation state.