Chemistry Unit 1 Chapter 3

Chapter 3

Metals come from the Earth's crust. Some metals are very unreactive and are found as elements, in their native state. Metals, such as zinc, iron and lead, are found combined with oxygen in compounds. These metals can be extracted using chemical reactions. The metal oxides are reduced as oxygen is removed from the compound.

Iron (III) oxide is pure (has its oxygen removed) in a blast furnace. Iron from the blast furnace, poured into moulds and left to solidify is called cast iron. If all the carbon and other impurities are removed from cast iron we get steel iron. Iron that has been alloyed with carbon and other elements is called steel. Iron that contains just a small percentage of carbon is called carbon steel.

Aluminium and titanium alloys are useful as they are strong and have a low density. Although aluminium is reactive, it does not corrode because its surface is coated with a thin, tough later of aluminium oxide. Titanium does not corrode because it is not very reactive and also has its oxide layer to protect it. We use large amounts of energy in the extraction of both metals from their ores which makes them expensive. The large number of steps involved in the extraction of the metals also contributes to their high cost.

Traditionally, copper can be extracted from some of its ores by heating (smelting). If copper ore is treated with sulphuric acid, we get a solution of copper sulfate. We can obtain copper metal from this solution either by adding low metal or by passing electricity through the solution. Now new ways are being developed to extract copper using bacteria (bioleaching) or plants (phytomining). There can extract the commper from low-grade o 

The transition metals are found in the central block of the periodic table. Like pure iron, pure copper is too soft to be very useful. We can make copper harder by alloying it with tin to make aluminium, and with zinc to make brass.

After a open-mine shaft is no longer being economically used, the company could cover up the hole, so the possibility of the wildlife that used to grow there coming back would be there and water doesn't seep and become infected and dirty.

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