chemistry
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
atoms, elements and compounds
> 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
limestone and it's uses
> 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
Decomposing carbonates
> when water is added to quicklime it makes slaked lime.
> lime mortar is made by mixing slaked lime with sand and adding water
quicklime and slaked lime
> 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
cement, concrete and glass
> 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
extracting metals
> 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
extracting iron
> 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
properties of iron and steel
> 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
alloys in everyday use
> 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
transition metals
> 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
aluminium and titainium
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