The higher the metal in the series, the more reactive it is i.e., its reaction is fast and more exothermic.
This also implies that the reverse reaction becomes more difficult i.e., the more reactive a metal, the more difficult it is to extract from its ore. The metal is also more susceptible to corrosion with oxygen and water.
The reactivity series can be established by observation of the reaction of metals with water, oxygen or acids.
A metal in the series, can displace any metal below it in the series, from the oxide, chloride or sulphate of the less reactive metal.
Copper (II) sulphate solution is blue, iron sulphate solution is almost colourless when dilute. During the displacement,
the blue solution loses its colour, and the iron metal is seen to turn pink-brown as the displaced copper becomes
deposited on it.
On heating the mixture of magnesium powder and black copper(II) oxide, white magnesium oxide is formed with
brown bits of copper:
Adding magnesium to blue copper(II) sulphate solution, the blue colour fades as colourless magnesium sulphate is
formed and brown bits of copper metal form a precipitate:
Hydrochloric acid makes a metal chloride
Sulphuric acid makes a metal sulphate
Reactions with nitric acid are complex, the nitrate is formed but the gas is rarely hydrogen, and more often, an oxide of nitrogen.
Within the general reactivity or activity series there are some periodic table trends:
Down Group 1 (I) the "Alkali Metals" the activity increases Cs > Rb > K > Na > Li. Down Group 2 (II) the activity
increases eg Ca > Mg. On the same period, the Group 1 metal is more reactive than the group II metal, and the
group II metal is more reactive than the Group III metal, and all three are more reactive than the "Transition
Metals". eg Na > Mg > Al (on Period 3) and K > Ca > Ga > Fe/Cu/Zn etc. (on Period 4)
Two non-metals, carbon and hydrogen are important chemical reference points with regard to the method of metal
extraction and reactivity towards acids. Metals above carbon cannot be extracted by carbon reduction and are
usually extracted by electrolysis. Metals below hydrogen will not displace hydrogen from acids:
The higher the metal in the series, the more reactive it is i.e., its reaction is fast and more exothermic. 
