The Reactivity Series of Metals
Metals Arranged in Order of their Ability to React
Share Article Feb 27, 2010 Simon Davies
Metals are very important substances in today's world. Gold, silver and alloys of copper form the basis of our currencies. Iron, and its alloy, steel, is used in the construction of buildings, cars and many other structures. Copper wires are still vital for our electrical installations, and many alloys (mixtures of metals) are used in the everyday gadgets taken for granted throughout the world.Increasing ReactivityWhen different metals are compared, however, it is obvious that they are not all the same. They are all defined as metals due to their structure and bonding, which distinguish them from non-metals, but they have greatly varying chemical properties. It is obvious to any car owner, for example, that iron rusts but gold does not.Sodium is also a metal, but when a small piece is placed in water, a violent reaction occurs. Gold seems almost completely unreactive. These differences are reflected in both the history of the use of metals and in the techniques used for their extraction.Different Methods of ExtractionThe least reactive metals, gold and silver, are found as metals in the earth's crust. It is possible to find small pieces of gold in certain types of rock. Other metals, because they are more reactive, are found in ores, combined in compounds with other elements, especially as oxides, combined with oxygen from the air.Some of these metals, including copper, zinc and iron, can be extracted easily, by mixing the ore with carbon from coal or coke and heating it in a blast furnace. This is because the metals are less reactive than carbon, so the oxygen in the ore prefers to combine with carbon than with the metal. This extraction method has been used for more than 2,000 years and the metals have been widely used throughout human history.Extraction by ElectrolysisThe more reactive metals hold on tighter to the oxygen, so their extraction has only developed since the 19th century. In the days of Napoleon III, emperor of France from 1848-1873, aluminium utensils were considered more precious than gold. Today these metals can be extracted by electrolysis of the melted ores.The ReactivityThe reactivity series of the metals, therefore, has potassium, sodium and lithium at the top. These metals react readily with both the air and water – potassium actually melts and catches fire when placed in water. Calcium and magnesium come next – they burn easily in air and react more slowly with cold water.Aluminium, zinc and iron are much less reactive. They have very slow reactions with air, but will burn if powdered or shredded into wool, and will react with steam. Copper reacts very slowly with air and has no reaction with pure water. Finally come silver and gold, which do not react with either air or water. Of course, copper and silver do seem to react with the air or rainwater (silver tarnishes and copper roofs turn green) but this is actually due to acidic constituents of the air and rainwater. Silver does not react with oxygen, copper does not react with pure water.References:The Reactivity Series, Dr Colin France, gcsescience.com, accessed on 28-02-10Chemistry for GCSE, Colin Johnson, Heinemann, UK, 1987.
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