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C1 (1) (Element Patterns (Reactive and Unreactive (The number of outer…
C1 (1)
Element Patterns
Reactive and Unreactive
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The periodic table lists all known elements by increasing proton number. It has horizontal rows called Periods, and vertical groups called Groups
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Atoms, Elements and Compounds
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Modelling Structures
Symbols are not always the letters of the name of the element. Sodium has the symbol Na from Natrium, the Latin word for salt
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Inside the Atom
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Sub-atomic particles
Have both a charge and a mass(can be worked out the mass number by adding together the number of protons and neutrons)
Since an atom has equal numbers of protons and electrons, the charges cancel out
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Combining Atoms
Eight in a Shell
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Atoms with fewer than eight outer electrons react in ways that give them a stable group of eight in their outer shell
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Chemical Equations
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Balancing Equations
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Start with metal atoms, leave the hydrogen and oxygen till the end
Building with Limestone
Limestone Quarry
Advantages
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More, better-paid jobs, so more money to boost local economy
Better healthcare and leisure facilities, as more people move into the area
Better transport links, needed for lorries or railways
Disadvantages
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Noise and vibration from blasting,machinery and vehicles
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Limestone Caves
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This produces caves and potholes. When water evaporates it reverses the process producing stalactites and stalagmites(solid calcium carbonate)
Heating Limestone
Cement
Calcium hydroxide solution(limewater) is used to test for carbon dioxide.If carbon dioxide is bubbled through limewater, it turns cloudy as tiny solid particles of white calcium carbonate form
Cement(made by heating limestone an clay) is used widely on its own, in mortar or concrete
Mortar(mixing sand, cement and water) binds bricks together
Concrete(mixing cement, and, gravel and water) is very strong and is used for foundations of buildings or structures
Mortar vs Concrete
Cement, mortar and concrete do not dry out. The cement reacts with the water to form crystals that 'cement' the mixtures together
In concrete the mix of small sand particles and various sized stones in concrete makes it much stronger than mortar
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Making from Ores
Making use of ores
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At the smelter, the ore is crushed and concentrated,to remove rock with little or no metal
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To convert the metal oxide to the metal, the oxygen must be removed(reduction)
The metal oxide is reduced by heating it in a furnace with carbon if the metal is below carbon in the reactivity series. Originally, the carbon was charcoal, but now it is coke(a nearly pure form of carbon, from coal)
Limestone is often added, to remove impurities in the ore forming slag
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Extracting Iron
Inside a Blast Furnace
Iron ore, coke and limestone are fed in at the top of the furnace
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As the hot air is blown through, the coke burns in oxygen to produce carbon monoxide
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The carbon monoxide then reduces the iron oxide to iron, and is oxidised to carbon dioxide
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The limestone reacts with impurities in the ore to make slag, this floats on top of the iron
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Metals are Useful
Atoms and Alloys
Meta atoms are arranged in giant structures, in regular rows and layers
Metals can bend because these layers can slide over each other(shape can change but atoms remain together)
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Smart Alloys
These alloys can remember their original shape, and if warmer return to that shape
To mend broken bones, strips of smart alloy are cooled, stretched and screwed onto the bone. As the strips warm up they shrink, pulling the bones back together so the break heals faster and in the correct position
Iron and Steel
Designer Steels
Pure iron is too soft for most uses, so steels are used instead
Adding other metals to molten steel can give it special properties. The choice of metal depends on how the steel will be used, and therefore the properties are required
Stainless steel is about 70% iron, 20% chromium and 10% nickel. Stainless steel is very resistant to corrosion and does not rust
Metal added to Steel
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Molybdenum and/or tungsten(more strength, hardness and toughness)
Vanadium(more strength, less brittle)
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