Location: Outside U.S.
Why are some metals non-reactive?
Unfortunately, this is a very big question. When we say any substance
in non-reactive, we always have to follow with, "Under what conditions?"
Sodium, considered a reactive metal (we know that it readily reacts
with moisture in the air), can be made relatively inert by immersing
it in oil. For as long as the sodium is under oil (not in contact with
water and there is a coating of sodium hydroxide around most of the
metal), the metal is relatively stable.
In general, we consider any substance non-reactive if it takes quite
a bit of energy to get it to react with most substances. A non-reactive
substance then must have very low internal energy, is stable, and needs
to be activated (its internal energy increased) before it can start
Greg (Roberto Gregorius)
You have to be careful about how you define "non-reactive". There are
several variables: "Non-reactive" with what, and under what conditions?
Copper metal, in the presence of dry air is fairly non-reactive. But
in the presence of water and acids or bases reacts pretty quickly.
Similarly, silver in dry air is inert, but add a little hydrogen
sulfide, and it will tarnish (react) quickly.
Aluminum metal at neutral pH ~ 7 is inert, but at pH>~9 or less than
< ~5 reacts with water very quickly.
"NON-REACTIVE" is a relative term. The co-reactants and conditions have to
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Update: June 2012