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| Introduction |
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| Earth is an abundant source of material. Man has intensively studied the properties of these materials extensively and found new methods of using them. The air we breathe, the water we drink, stones and rocks, almost everything that is around us, are all useful to man for some purpose or the other. These materials are distributed in the atmosphere, lithosphere, and hydrosphere. Oxygen, Nitrogen and Carbon di oxide are found in the atmosphere. Common salt and various other salts of sodium, magnesium and calcium are found dissolved in water bodies, like the oceans, rivers and lakes. |
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| The wealth of a nation depends on its natural resources. The progress of the civilization was benchmarked by mans increasing knowledge and usage of metallic deposits in the earths crust. The first metals to be found and used were copper, silver and gold as they could be easily extracted. Early man used stones, bones and wood to fulfill their requirements of hunting, cooking and building. By 2000 B.C. iron could be extracted from its ores by heating and this period came to be known as “Iron Age”. Bronze was widely used for many years and this epoch of prehistory became “Bronze Age”. They indicate a gradual change in the life style of mankind. |
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| About 7000 years ago it was discovered that certain minerals would yield metals when placed in the fire. Many of these colored minerals were used as glazes to impart color or texture to pottery. So the first production of metals from their ores was probably a byproduct of pottery. As time went by, minerals were found to produce metals with different properties. The metals and non-metals are characterized by distinctly different physical and chemical properties. It is hard to overestimate the impact that metals have had on the history of our society. Metals can be shaped like clay, are heat-resistant, and are not fragile . There are about 103 elements, 92 of which are naturally occurring. At present about 80 metals are known to us. At room temperature, over half of the non-metals are gases except bromine which is a liquid. |
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| The first metals were found in their elemental or "native" state. Only three metals are found this way, copper, silver, and gold. At first, these meatls were used for ornamental or traditional purposes, and not for utilitarian usage. Also they were soft for utilitarian uses. All metals are not shiny like silver (Ag), gold (Au), or platinum (Pt). |
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