A list of elements (usually metals) arranged in an order to show how easily they form compounds.

Any element in the list will always be able to reduce (take oxygen away from) the oxide of an element lower down in the list.

Some elements arranged in order of chemical activity. The rate of chemical reactivity increases as you go up the list

Example 1 Reacting metals with dilute hydrochloric acid

Method:
1 spatula each of powdered magnesium, powdered zinc, iron filings and copper turnings are each placed separately in a test tube containing equal volumes of dilute hydrochloric acid. All observations are noted

Results

Explanation:
Metals react with an acid to produce hydrogen gas.
The reactive metals like magnesium reacted much more vigorously than the less reactive metals like zinc and iron.
The test for hydrogen is that it burns with a squeaky 'pop'.

Example 2. heating magnesium powder with copper oxide

Some copper oxide is mixed with powdered magnesium on a crucible lid and heated strongly

Result:
A violent exothermic reaction. The copper oxide was reduced by the magnesium to leave magnesium oxide and copper.
(The heat of the reaction makes most of the copper turn back to copper oxide)

Word Equation: Magnesium + copper oxide  ---->  magnesium oxide + copper

The copper oxide has been reduced by the magnesium.
The magnesium has been oxidised by the copper oxide.

The reaction above shows us that magnesium is MORE reactive than copper.

Example 3.
Heating zinc powder with magnesium oxide

result:
NOTHING will happen.
The zinc cannot reduce the magnesium oxide. This shows us that zinc is LESS reactive then magnesium.

Example 4:     A Displacement reaction
Some iron filings are placed in a blue solution of copper sulphate

Result:
The copper sulphate loses its colour and the iron goes pink because it gets a coating of pink copper.
the solution also gets warm which shows that a chemical reaction is taking place.

Explanation: The iron is more reactive than copper and displaces (pushes out) the copper from the solution.

Word equation: Copper sulphate + Iron ----> iron sulphate + copper

Example 5 If Some magnesium ribbon is plunged into a gas jar containing carbon dioxide gas the magnesium will reduce the carbon dioxide to leave black specks of carbon and magnesium oxide

Word equation: Magnesium + carbon dioxide ---> magnesium dioxide + carbon

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Example 6:      Reaction between a metal and water
Certain very reactive metals like calcium and sodium are so reactive that can react with water producing hydrogen gas (burns with a squeaky pop).

Calcium metal will reduce water to form hydrogen gas and leave a white residue of calcium oxide.
This reaction shows us that calcium is more reactive than hydrogen.

(* remember that water is an oxide of hydrogen)

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New Vocabulary:
Reduce: To take oxygen away from a compound.

Oxidise: When a chemical gets oxygen added to it

Displace: When a metal is pushed out of a solution by another, more reactive metal

Exothermic: A reaction which gives out heat

examples:

1.When magnesium reacts with copper oxide the magnesium is oxidised and the copper oxide is reduced.

2. When iron is added to copper sulphate solution the copper is displaced by the iron.

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