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Chemistry Unit 1 (Changing Planet (Carbon Cycle (Plants + animals die -…
Chemistry Unit 1
Key Ideas
Atomic Structure
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Protons have positive charge, Neutrons have no charge + Electrons have negative charge
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Atomic Number - number of protons/electrons in element + elements are arranged in order of atomic number in periodic table
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Electron Arrangement
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Electrons in each shell - 2, 8, 8, 8
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Forming Bonds
When a metal reacts with non-metal --metal atoms lose electrons - positively charged + non-metal atoms gain electrons - negatively charged - they are now clled ions
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Uses of Metals
Extracting Metals
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Metals can be extracted by displacement using more reactive element - metals less reactive than carbon are extracted by heating with carbon
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Aluminium + Titanium
Aluminium
Aluminium - low density, high in reactivity series + resists corrosion
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Extracting copper
Phytomining - plants absorb copper compound from ground - plants are burned - copper extracted from ash
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Useful Metals
Transition Metals
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Many are strong but are malleable - useful in buildings, wiring + vehicles
Copper - good conductor - doesn't react with water - malluable but doesn't stay in shape - good for pipes + water tanks
Copper, Pure iron, Gold + aluminium are soft - often mixed to make alloys
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Crude Oil + Fuel
Fractional Distillation
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Gasoline, Kerosene, Diesel, Fuel Oil, Bitumen - differrent fractions
It condenses at different levels depending on boiling point - higher at the bottom + lower at the top
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Burning Fuels
Incomplete combustion - due to oxidisation can produce carbon monoxide + some hydrocarbons might not burn
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Cleaner Fuel
Burning any fuel containing carbon produces CO2 + incomplete combustion causes CO - causing global dimming
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Biofuel - made from animal + plant products - renewable + Biodiesel - made from vegetable oils from plants
Products from Oil
Cracking
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Process - heating a mix of hydrocarbon + steam high OR passing hydrocarbon vapours over hot catalyst
Thermal decomposition in cracking produces a mix of small molecules - some are alkanes + some are alkenes
Alkenes - CnH2n - unsaturated - double bonds - more reactive than alkanes - they react with bromine water turning it colourless
Polymers
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Ethene monomers joined together creates the polymer Polythene - double bond in ethene becomes a single bond + the other bonds join together with more monomers
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Plastic Waste
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Natural polymers include wool, silk + wood
Ethanol
Fermentation
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Yeast, sugar + water in a conical flask connected to test tube containing lime water with tube
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Plant Oil
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Vegetable Oils - provide nutrients + energy for fuel - steam distillation sometimes used to extract it
Steam Distillation - water is heated + evaporates + mixes with lavender or any other plant + then enter condensation chamber producing water + lavender oil.
Hydrogenation/Hardening - unsaturated oils reacted with hydrogen so they become single bonds - have higher melting points - solid are room temp
Emulsions
Emulsion - tiny droplets of one liquid spread through the other liquid (oil + water) - thicker than either of the liquids
Examples - Milk, cream + ice cream
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Changing Planet
Plate Tectonics
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Magma in mantle heated by core + becomes less dense + rises - gets more dense + drops to get heated by heat from radioactive activites
Subduction - Oceanic crust goes under Continental crust (causing earthquakes) - rock can melt + rise to form volcano
Alfred Wegener - created idea of continental drift in 1915 - not accepted (didn't know why it happened) - Plate Tectonics developed in 1960s.
Earth Structure
From the centre out - Inner + Outer Core, Mantle, Crust, Atmosphere
Crust - thin solid - about 5km to 70km thick - raw materials we need are here, atmosphere + oceans
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Earth has diameter of 12,800km
Atmosphere in Past
Originally Earth was covered in volcanoes releasing CO2, water vapour + nitrogen
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Next 2 billion years - algae + plants evelved - used CO2 for photosynthesis + released oxygen - plants increased so less CO2 + more Oxygen
Life on Earth
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Miller-Urey Experiment
Used a mix of water, ammonia, methane + hydrogen + high voltage spark to simulate what early life on earth would be like
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Other Theories
The organic molecules produced a Primordial Soup + amino acids combined to make the proteins from which life began
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Gases in Atmosphere
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Fractional Distillation of liquid air - separates gases in air - each have different boiling points - cooled to below -200°C
Carbon Cycle
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Because of these constant processes the amount of CO2 in atmosphere has stayed the same for past 200 million years