all topics

  • Created by: niki
  • Created on: 01-04-11 18:57

> all substances are made up of atoms

> elements contain only one type of atom

>different atoms can bond together by giving, taking or sharing electrons, to form compounds

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atoms, elements and compounds

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> limestone is made mainly of calcium carbonate

> limestone is widely used in building

> limestone breaks down when we heat it strongly (thermal decomposition) to make quicklime and carbon dioxide

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limestone and it's uses

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> some carbonates decompose when we heat them in a bunsen flame

> there is the same number of each type of atom on each side of a balanced equation

> the mass of reactants is the same as the mass of the products in a chemical reaction

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Decomposing carbonates

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> when water is added to quicklime it makes slaked lime.

> lime mortar is made by mixing slaked lime with sand and adding water

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quicklime and slaked lime

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> cement is made by heating limestone with clay in a kiln

> concrete is made by mixing crushed rocks, cement and sand with water

> glass is made by heating powdered limestone, sand and sodium carbonate together very strongly

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cement, concrete and glass

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> the earths crust contains many different elements

> a metal ore contains enough of the metal to make it economically worth extracting

> we can find gold and other non-reactive metals int heir native state

> the reactivity series is useful in deciding the best way to extract a metal from it's ore

> metals more reactive than carbon cannot be extracted from their ores using carbon

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extracting metals

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> we extract iron from iron ore by reducing it with carbon in a blast furnace

> the solid raw materials to make iron are iron ore (haemetite), coke and limestone

> molten iron is tapped off from the bottom of the blast furnace

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extracting iron

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> pure iron is too soft for it to be very useful

> carefully controlled quantities of elements are added to iron to make alloys of steel with different properties

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properties of iron and steel

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> copper, gold and aluminium are alloyed with other metals to make them more useful

> we can control the properties of alloys by adding different amounts of different elements

> smart alloys are also called shape memory alloys. When deformed the return to their original shape on heating

> shape alloy memories can be used in medicine and dentistry

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alloys in everyday use

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> the transition metals are found in the middle block of elements in the periodic table

> transition metals have properties that make them useful for building and making things

> copper is a very useful transition metal because of its high conductivity

> scientists are looking for new ways to extract copper that will use less energy

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transition metals

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> aluminium and titainium are useful because they resist corrosion

> aluminium and titainium are expensive because extracting them from their ores requires large amounts of energy

> recycling aluminium is important because we need much less energy to produce 1kg of recycled aluminium than we use to extract 1 kg of aluminium from its ore

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aluminium and titainium

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