Chemistry 1

1. Chemistry 1

2. The structure of the atom Electronsin shells Neutronin nucleus Protonin nucleus

3. Mass and atomic number MASS NUMBER = number of protons+ number of neutrons 4 He SYMBOL 2 PROTON (ATOMIC) NUMBER = number of protons (or electrons)

4. Symbols Elements are represented by symbols 1 11 16 H B O 1 5 8 23 35 238 Na Cl U 11 17 92

5. Elements, compounds & mixtures Elements – contain one type of atoms Mixtures – twoor more elements notchemically joined Compounds – twoor more elementschemicallyjoined

6. Periodic table At Os Ba La Hf Ta W Re Ir Te Pt Au Hg Pb Bi Rn Po Rb Sn Ra Cs Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Fr Sb I Tl K Sc Xe V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Ca Br Kr Ti Mg Al Si Na S Cl Ar Li P B C N O F Be Ne H Reactive metals Non-metals Transitionmetals Noble gases Mendeleev Other metals Separates metals andnon-metals He Columns called groups Rows called periods

7. Electron structure 39 K 19 Potassium has 19 electrons. These electrons occupy specific energy levels “shells”… Nucleus The inner shell has 2electrons The next shell has 8electrons The next shell has 8electrons The next shell has the remaining 1electron Electron configuration = 2.8.8.1

8. Compounds Sodium chloride (salt) Methane Glucose Compounds are formed when twoor more elementsare chemically combined. Some examples:

9. Covalent bonding Atoms sharing electrons is called covalentBONDING. This bonding occurs between non-metalsatoms. Each atom make enough covalent bonds to fill it’s outershell Hydrogen has just 1electron in its outer shell. A full (inner) shell would have 2electrons, so two hydrogen atoms get together and “share ” their electrons: Now they both have a fullouter shell and are more stable. The formula for this molecule is H2.

10. Ionic bonding This is where a metalbonds with a non-metal. Electrons are transferredbetween atoms. Metal atoms loseelectrons to form positive ions Non-metals gainelectrons to form negative ions Sodium in Group 1 has 1 electron on its outer shell Chlorine in Group 7 has 7 electrons in outer shell. Sodium transfers 1 electron – so both atoms have a fullouter shell and are stable. Positive and negative charges attract Na Cl + - Na A negativelycharged chloride ion A positivelycharged sodium ion Cl

11. Limestone Limestone is a sedimentaryrock made up of mainly calcium carbonate. It’s cheap and easy to obtain by quarrying. • Uses • Buildingmaterials • Making cement. CaCO3 heated with clay • Making mortar. Cement mixed with sand and water • Makingconcrete. Cement mixed with sand and aggregate • Neutralisingacidic soil & lakes - slaked lime

12. Limestone Positives of quarrying • Provides jobs • Provides materials • Provides neutralisationproducts Negatives of quarrying • Destroys habitats • Produces noiseand dust • Transportations makes pollution • Destroys landscape

13. The “Limestone Cycle” Calcium Carbonate (CaCO3) + water Step 1: CaCO3 heated – thermaldecomposition Step 3: add carbon dioxide to slaked lime calcium oxide + carbon dioxide CaO (quicklime) + CO2 calcium hydroxide Ca(OH)2 (slaked lime) Step 2: add water to quicklime

14. Metal extraction • Metals can either be found nativein the ground (e.g. gold) or are found as metal ores (e.g. iron = haematite, aluminium = bauxite) • Metals • abovecarbonextracted by electrolysis • belowcarbon extracted by reduction • silverand goldfound native potassium sodium calcium magnesium aluminium carbon zinc iron lead copper silver gold increasing reactivity

15. Reduction carbon zinc iron lead copper Reduction is the removal of oxygen The metaloreis reacted with carbon. The carbon is more reactiveso removes the oxygenfrom the ore iron oxide + carbon  carbon dioxide + iron

16. Electrolysis ---- potassium sodium calcium magnesium aluminium carbon Electrolysis is breaking down a substance using electricity It needs a liquidto conductelectricity. High temperaturesare needed, which needs a lot of energy making it expensive Positive electrode made of impurecopper – loses Cu2+ ions = shrinks Negativeelectrode made of purecopper – gains Cu2+ ions = grows + + + + Cu2+ Cu2+ Solution containing copper ions

17. Bioleaching & phytomining New mining techniques used to extract copperand decrease the effects of metal extraction on the environment. Bioleachinguses bacteriato separate copper from coppersulphide. The solution produced (leachate) contains copper which can be filtered. Phytomininguses plants grown in soil containing copper, which builds up in leaves. Leaves burnt and copper in ashcan be collected.

18. Recycling metals • Fossil fuels running out • Recycling uses less energy than mining • Recycling saves money • Recycling cuts down on landfill sites • Recycling reduces amount of pollution

19. Properties of metals Ra Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Pd Ag Bi Po At Rn Rb Sr Y Zr Nb Mo Tc Ru Rh Tl Pb Cd Ni Sn Sb Te I Xe K Ca Sc Ti V Cr Mn Fe Fr In Cu Zn Ga Ge As Se Br Kr Na Mg Al Li Be Co • Strong • Can be bent • Can be hammered • Good conductors of heatand electricity

20. Copper, Aluminium and Titanium

21. Alloys Gold mixed with copper Aluminium mixed with magnesium and copper Aluminiun mixed with chromium An “alloy” is a mixtureof metals. Alloys are harderthan pure metals

22. Using Iron Steel with chromium and nickel is called stainless steel Steel with a high carbon content is strong but brittle Steel with a low carbon content is easily shaped Iron produced by the blastfurnacecontains about 96% iron and 4% impurities. These impurities make it very brittleand easy to break. Iron is alloyed to make steel.

23. Crude oil Decreasing temperature Crude oil is a mixture of hydrocarbons (only contains elements hydrogenand carbon) The separate parts – fractions – can be extracted by fractionating distillation Crude oil piped in at bottom of fractionatingcolumn, heated, oil evaporates and rises. Fractionscondenseand are collected

24. Alkanes Alkanes are saturatedhydrocarbons -all of the atoms are held together by single bonds. General formula is CnH2n+2 - twiceas many hydrogen atoms as carbon atoms plus an extra two Ethane – C2H6 Methane – CH4 Propane – C3H8 Butane – C4H10

25. Patterns Increasing length Longer chains mean… • More viscous(gloopy) • Less flammable • Higher boiling point

26. Fuels A fuel is burnedto release energy Coal, oil and gas are fossilfuels.

27. Burning Fossil Fuels H H H H O O O O O O O O O O O H H C C C C H H H H H H Burning fossil fuels (combustion) releases gasesand particles Completecombustion (plenty of oxygen) produces carbondioxideand water Carbon dioxide is a “greenhousegas” – cause global warming Incompletecombustion (not enough of oxygen) produces carbon monoxide and carbon Carbon monoxide is a poisonous gas

28. Sulphur dioxide Burning coal releases sulphur dioxideandnitrogen oxides Sulphur dioxide and nitrogen oxides cause acid rain and “global dimming” – sunlight is absorbed by the particles in the atmosphere. Acid rain kills trees, causes lakes to become acidic killing wildlife and damage limestone buildigns and statues

29. Alternative fuels

30. Cracking Usefulshortchain hydrocarbons can be made from long chain hydrocarbons by “cracking”: Gaseous hydrocarbon Long chain hydrocarbon Heated catalyst Liquid hydrocarbon Long chain hydrocarbon heated to thermally decompose. Hydrocarbon vaporises, passes over a catalystand splitsinto an alkaneand an alkene

31. Alkenes Alkenes are unsaturatedhydrocarbons –there is a doublebond between 2 carbon atoms. General formula is CnH2n - twiceas many hydrogen atoms as carbon atoms Ethene – C2H4 Propene – C3H6 Butene – C4H8

32. Testing for alkenes Orangebromine water Unsaturated alkene Colourlessbromine water

33. Making ethanol • Ethenereacted with steamin presence of catalyst. Ethene comes from crude oil – will eventually run out • Sugar fermentedwith yeast. Carbon dioxide also produced. Sugar grown - renewable

34. Monomers and Polymers n n C C C C Alkenescan be used to make polymers(plastics) Lots of small alkene molecules – monomers – are joinedtogether to make very large molecules – polymers Ethene  poly(ethene) Propene poly(propene) Ethene Poly(ethene)

35. Properties & uses of polymers • Lightand stretchy– used for plastic bags • Elastic– used to make Lycra • Waterproof– fabric coating • Non-biodegradable– don’t rot

36. Extracting plant oils • Extracted from fruitsand seeds • Plant material is crushed, pressedand filteredto remove impurities

37. Emulsions Emulsions are a mixture of oiland water. Dropletsof one liquid are suspendedin the other liquid. Emulsions are thickerand have lots of uses – mayonnaise, ice cream andpaintare examples Emulsifiersstop emulsions from separating – e.g. egg yolk

38. Emulsifiers - HT Emulsifiers have a hydrophilic(likes water, hates oil) part emulsifier water hydrophobic(likes oil, hates water) part. oil

39. Saturated and unsaturated oils Vegetableoils are unsaturated. They have a carbon-carbon double bond. Tested for bromine water

40. Hydrogenating oil- HT Unsaturatedvegetable oil can be hardenedby reacting them with hydrogenin the presence of a nickel catalystat 60oC. Hydrogenadds to the carbon-carbon double bond. Hydrogenated oils have higher melting points = solid at room temperature. Useful for cakes and pastries

41. The Structure of the Earth Thin crust- 10-100km thick Mantle– has properties of a solidbut it can also flow Core– made of molten nickeland iron. Outerpart is liquidand innerpart is solid

42. Tectonic plates The Earth’s crustis split up into tectonicplates: These plates are moving apart from each other a few centimetres every year due to convection currents in the mantlecaused by the radioactive decay of rocksinside the core.

43. Tectonictheory • It was once thought that the oceans and the continents were formed by shrinkagefrom when the Earth cooled down after being formed. • Alfred Wegenerproposed that there was once a single land mass, that has changed as tectonic plates moved - TECTONIC THEORY. The evidence he had was • the continents look like they “fit” together. • had similar rock patterns and fossil records.

44. Tectonic theory Wegener couldn't explainhow continental drift happened so nobody believed him The Answer: • Scientists discovered 50 years later that the Earth generates massive amounts of heat through radioactive decay in the core. This heat generated convection currents in the mantle causing the crust to move • We also now know that the sea floor is spreadingoutwards from plate boundaries

45. Movement at boundaries Movement of plate boundaries can be suddenand disastrous. Earthquakesand volcanoeshappen at the boundaries between tectonic plates

46. Evolution of the Earth’s Atmosphere Carbon Methane Ammonia Oxygen Nitrogen Others dioxide 4 Billion years 3 Billion years 2 Billion years 1 Billion years Present day Present day atmosphere = 78% N, 21% O2, 1% noble gases and about 0.03% CO2 Phase 1 – volcanoes give out CO2, H2O, CH4& NH4. Water vapour and carbon dioxide condensed to form oceans Phase 2 – green plants evolved, using up CO2and producing O2.