| The discovery of new elements (pre-16) |
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Robert Bunsen – flame colours |
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Robert Bunsen (1811 - 1899) and Gustav Kirchoff (1824 - 1887) were early users of the technique of examining the light given out by heated compounds to recognise new elements. Have you noticed that a wire dipped into sodium chloride solution gives an intense yellow flame colour or that when a pan of salted water boils over it colours the gas cooker flame yellow? This colour is characteristic of sodium and is also seen in street lamps that are filled with sodium vapour. A development of this method is still used today to measure the amounts of certain elements in mixtures. Activitya) The flame colours of some metals are clear enough to be used to identify them by eye – the orange-yellow colour of sodium is an example. Make a list of flame colours of metals that you know, then use an internet search to check your answers and fill in some you are not familiar with. b) The element helium was discovered from its spectrum. Find out using an internet search what was unusual about this discovery. |
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