Chemistry - Unit 1 chemistry notes 3.5 / 5 based on 2 ratings ? ChemistryGCSEAQA Created by: tanyaCreated on: 28-03-10 21:21 Atoms, Elements and Compounds All substances are made of ATOMS. substances made up of only one atom are called ELEMENTS elements are arranged in the periodic table in vertical columns called GROUPS different atoms join together to form COMPOUNDS atoms are made up of tiny central NUCLEUS with ELECTRONS orbiting around it two or more atoms bonded together are called a MOLECULE different atoms bond together by GIVING, TAKING or SHARING ELECTRONS 1 of 5 Limestone and its uses limestone is made up of mainly CALCIUM CARBONATE POWDERED LIMESTONE can be heated with SAND and SODIUM CARBONATE (soda) to make GLASS POWDERED LIMESTONE can be heated with POWDERED CLAY to make CEMENT when CEMENT POWDERED, WATER, SAND and CRUSHED ROCKS are mixed together a slow reaction takes place to produce CONCRETE when we heat LIMESTONE strongly it breaks down to form QUICKLIME (calcium oxide) CARBON DIOXIDE is also produced from this process breaking down a chemical by heating is called THERMAL DECOMPOSITION to make lots of QUICKLIME the reaction is done in a LIME KILN calcium carbonate ----(heat)--- calcium oxide + carbon dioxide LIMESTONE is widely used in BUILDINGS 2 of 5 Qiucklime and Slaked Lime when we add water to quicklime it reacts to produce SLAKED LIME (calcium hydroxide) and it gives out a lot of HEAT calcium oxide + water ------ calcium hydroxide CaO + H2O ------ Ca(OH)2 we can dissolve calcium hydroxide in water and filter to produce LIMEWATER LIMEWATER goes cloudy when CARBON DIOXIDE is added as CALCIUM HYDROXIDE is produced calcium hydroxide + carbon dioxide ------ calcium carbonate + water Ca(OH)2 + CO2 ------ CaCO3 + H2O MORTAR can be made by adding SLAKED LIME, SAND and WATER MORTAR is used for building as it reacts with the CARBON DIOXIDE in the air producing CALCIUM CARBONATE again 3 of 5 Cement, Concrete and Glass heating LIMESTONE with CLAY in a kiln produces CEMENT when we mix LIMESTONE, CLAY and OTHER MINERALS and then heat and grind into a fine powder PORTLAND CEMENT is produced WATER + CEMENT + SAND + CRUSHED ROCKS = CONCRETE pouring CONCRETE around STEEL RODS or BARS then allowing to set strengthens the CONCRETE. this is called REINFORCED CONCRETE POWDERED LIMESTONE + SAND + SODIUM CARBONATE = GLASS 4 of 5 Extracting Metals the EARTHS CRUST contains lots of metals a rock containing enough of a metal is called a metal ORE 5 of 5
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