...does rust only happen with copper or materals contaning copper?? if so then why do ather metals rust??
As Nobby indicated, copper is not required, but can enhance rusting.
More properly, you should be talking about the
oxidation of metals. Oxidation is the process where a compound (in this case the metal) donates an (or multiple) electron to form a positively charged state (in the case of Iron, this is Fe --> Fe
n+ + n e
-, where n = 2 or 3).
In order to complete the reaction -remember, a positive charge cannot remain stable unless counterbalanced by a negative charge- another compound (in the case of iron rusting, oxygen from the air) must take up the electrons that the metal is donating. In case of oxygen
reduction, this goes according to: O
2 + 4e
- --> 2 O
2-.
Now when water is present, this reaction turns initially to O
2 + 2H
2O + 4e
- --> 4 OH
-. Why? Because this reaction requires less energy. This is why water facilitates the formation of iron rust outside.
In acidic environment, the reaction becomes: O
2 + 4H
+ + 4e
- --> 2 H
2O, this reaction is even more preferred than merely the reduction of oxygen in water. That is why acid rain is so bad for metal objects outside and will cause them to rust faster.
Now said that ALL metals oxidize, that is the truth. However, there are metals more stable -more commonly said to be more "noble"- than others. The most stable of the common metals is gold, which is thermodynamically stable, even in acid environment.
The reason copper enhances the iron oxidation has something to do with this stability. In time, copper will also oxidize, but when it is in contact with iron, another reaction ("contact corrosion") will happen where the copper (hydr-)oxide thus formed will take up the electrons from the iron to reduce back to metallic copper. The iron will then of course oxidize even faster as it loses its electrons now to both the air and the copper it is in contact with.
To prevent contact corrosion, merely place an insulating layer between the copper and the iron.