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Conquering Chemistry - The Chemical Earth

Preliminary Textbook
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  MODULE 1 earth the chemical  The land, seas and atmosphere of planet Earth provide us humans with all the substances (or resources) we need for our survival, comfort and pleasure. Some of these resources we get from living matter—such as food and clothing from plants and animals, and timber for shelter from trees—but many of the resources we use come from the non-living Earth itself. This module will focus mainly upon the non-living resources.Some of the common substances (resources) we get from the Earth are:   coal, oil and natural gas for our energy needs   metals such as iron, aluminium and copper for making structures, machines and containers   gypsum for making plaster for houses   rock phosphate and sulfur for making fertilisers   sand and limestone for making glass and cement   silicon for making computer chips and solar cells   gold, diamonds and other gemstones for personal decoration   argon from the atmosphere for lling light bulbs.The photos below show some of these substances.The part of the earth we live in, the biosphere, consists of mixtures of many substances. Extracting the substances we want involves separating mixtures— extracting the required substance from the unwanted material. Often we need the substances we use to be pure, for example copper for electrical wiring and silicon for 2   MODULE 1 THE CHEMICAL EARTH  making solar cells or computer chips. Hence we need to be able to purify substances and use properties of the substances to determine whether or not they are pure. Because there are so many pure substances in the Earth, we frequently classify them into various categories. We can classify them into metals or non-metals, or we can group them into families of substances with similar properties (in what we call the Periodic Table).In this module then, we shall consider the ways in which people in general and chemists in particular separate mixtures into pure substances, and look at the common properties and uses of some of these pure substances. We shall survey the range of substances (elements and compounds) that make up the Earth and discuss some methods of classifying or organising them in Chapter 1.Most of the substances of the Earth are compounds rather than free elements. We shall therefore explore why and how elements combine to form compounds. This will require a look at the structure of atoms and a treatment of what is called chemical bonding, which is covered in Chapter 2.Many of the substances we want are not the pure compounds we extract from the Earth but rather substances we make from those raw materials—iron from haematite, aluminium from aluminium oxide, chlorine from salt. We get these wanted substances by what are called chemical reactions, introduced in Chapter 3. Because there are so many compounds in the Earth we need a system of naming them which tells us exactly what the compound is—in particular which tells us its chemical formula. Chapter 3 will also introduce systematic naming.  THE CHEMICAL EARTH MODULE 1   3 HARVESTING THE RESOURCES OF THE EARTH FROM LEFT: iron ore, bauxite for the production of aluminium, salt from sea water and sulfur for making sulfuric acid.
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