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This is simply a list of metals placed in order of decreasing reactivity. We shall see in this topic that the reactivity of a metal is related to its electrode potential. The more negative the electrode potential, the more reactive the metal is. The electrode potentials for a number of metals are tabulated below:
Most reactive
|
Metal |
Electrode potential (V) |
|
Potassium |
- 2.92 |
|
Sodium |
- 2.71 |
|
Magnesium |
- 2.37 |
|
Aluminium |
- 1.66 |
|
Zinc |
- 0.76 |
|
Iron |
- 0.44 |
|
Tin |
- 0.14 |
|
Lead |
- 0.13 |
|
(Hydrogen) |
0 |
|
Copper |
+ 0.34 |
|
Silver |
+ 0.80 |
Least reactive
A more reactive metal will replace a less reactive metal in one of its compounds. This type of reaction is known as a displacement reaction.
One of the most well-known displacement reactions is called the Thermit reaction. In this reaction the more reactive aluminium metal replaces the iron in iron(III) oxide:
|
Fe2O3(s) + 2Al(s) ⇒ 2Fe(l) + Al2O3(s) |
The reaction is highly exothermic and produces enough heat to make molten iron (it doesn't melt until 1535 ºC - so it's hot!). You will see the orange, glowing liquid metal flow from the base of the destroyed can in the following video:
The reaction is so bright that it "blinds" the camera which is why it appears to become night time suddenly!
The same reaction is used to weld railway tracks.