![]() Once the rock was red hot, he could crack it open by pouring cold water over it. The process was simplified when early man realised that he could light a fire under metal-bearing rock. Once found, mining it was laborious, difficult and dangerous. However, finding the copper and tin was still a problem. Bronzes of differing hardnesses could be made by mixing together different proportions of copper and tin and, because of this, bronze became the most important metal of its time. The Bronze Age started when copper and tin were mixed, probably accidentally, to make the alloy we now know as bronze - a much harder metal than either copper or tin alone. If the stones had happened to contain copper and/or tin compounds, the metals would flow out as liquids and quickly harden into lumps. This discovery may have been made accidentally by someone using a circle of stones to contain a fire. The first discovery of metals may have been as long ago as 8000 BC, but another 2,000 years passed before man learned how to smelt copper and tin from their ores. This was discovered by the North American Indians long before anyone learned how to smelt iron from its ore). ![]() (However, small amounts of unreacted iron have been found in the form of meteorites. The more reactive metals combine with non-metals, especially oxygen and sulphur, in rocks called 'ores'. They are called 'native' metals, because they are sufficiently unreactive to be found in the ground in their elemental forms. They would have been found in streambeds and rivers, washed out of the rocks. Gold, silver and copper were the first metals that early humans came across. This is so for copper and silver, but not for gold, for reasons which will be explained below. UnivalencyĮxamination of the electronic configurations of these metals found in the box above shows that atoms of these metals have a single electron in the outermost shell 4, like the alkali metals, and would therefore be expected to give univalent ions. Indeed they are often referred to as the 'coinage' or 'noble' metals. Because of this resistance to chemical attack, the metals are unreactive, including to atmospheric components such as oxygen and water 2, and have therefore been used for making coins and medals 3. Hence, attack by most reagents (such as oxygen or acids) is slow this resistance increases from copper through silver to gold.Ĭonversely, reduction of their compounds to the pure metal is easiest for gold, and diminishes through silver to copper 1. They are also found together at the foot of the reactivity series, which means that the metals are not easily oxidised to form positive ions. ![]() In the case of copper, silver and gold, these form a vertical triad, called Group 11, within the group of transition metals. In the Periodic Table of Elements, the chemical elements are organised according to their chemical and physical properties.
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