1 Elements and their atoms

1. 1 Elements and their atoms • Each element of the Periodic table is built from one type of atom • Atoms have a nucleus containing protons and neutrons, surrounded by electrons within energy levels (shells).

2. 2 Elements in groups • Elements in the same group of the Periodic table have the same number of electrons in the highest energy level (outer shell). • Elements in the same Group react in similar ways.

3. 3 Equations • Balanced equations describe reactions. • The reactants are on the left and the products are on the righte.g. CuO + CO = Cu + CO2copper oxide + carbon monoxide = copper + carbon dioxide

4. 4 Cement and concrete • Limestone is heated with clay to form cement. • Cement, water, gravel and sand form concrete.

5. 5 Metal carbonate decomposition • Metal carbonates are decomposed by heat to form metal oxides plus carbon dioxide.e.g. CaCO3→ CaO + CO2 • Calcium carbonate decomposes into calcium oxide and carbon dioxide • This is done in lime kilns.

6. 6 Calcium oxide and hydroxide • Calcium oxide reacts with water to form calcium hydroxide. • Calcium hydroxide solutions reacts with carbon dioxide to form calcium carbonate. This is the test for carbon dioxide.

7. 7 The ‘Lime’ cycle

8. 8 Transition elements • The elements in the middle of Periodic table are called transition metals. • They include metals in common use such as copper and iron

9. 9 Transition elements • Transition metals are hard, strong and have coloured compounds

10. 10 Alloys • Pure iron is converted into an alloy (steel) by mixing it with other elements. • This alters the arrangements of atoms.

11. 11 Pure metal & alloy structures • Pure iron is softer than its alloy, steel. • In pure iron the layers of atoms can slide over each other easily. • In steel, small atoms of carbon disrupt the layers and prevent sliding.

12. 12 Extracting metals from their ores • Metals are extracted from ores by electrolysis, or heating and reacting with carbon. • This is called reduction.

13. 13 Aluminium and titanium • Aluminium and titanium have low densities and do not corrode. • They are extracted using expensive electrolysis. • Recycling metals saves resources, energy and waste.

14. 14 What is crude oil? • Crude oil is a non-renewable resource. • It is a mixture of hydrocarbons • It is separated by fractional distillation.

15. 15 Alkane hydrocarbons • Alkanes are a family of saturated hydrocarbons • Saturated hydrocarbons contain only single covalent bonds. • Alkanes have the general formula CnH2n + 2

16. 16 Products of combustion Burning hydrocarbon fuels releases harmful substances: • carbon dioxide (greenhouse effect); • carbon monoxide (toxic); • sulphur oxides and nitrogen oxides (acid rain) and, • particulates(global dimming).

17. 17 Biofuels • Biofuels (biodiesel, bioethanol) are produced from plant material. • Producing biofuels releases less carbon dioxide overall and uses renewable resources. • It may reduce the amount of food crops the world can grow.

18. 18 Cracking • Cracking using heat and a catalyst breaks down long chain alkanes into smaller molecules including alkenes. • Cracking helps to produce more lighter oils which are in demand.

19. 19 Alkene hydrocarbons • Alkenes are unsaturated hydrocarbons which contain C=C double bonds. • Alkenes have the general formula CnH2n . • Bromine water is used to test for C=C double bonds. Alkenesdecolourise bromine water.

20. 20 Making polymers • Alkenes are used to manufacture polymers. • In polymerisation reactions many smaller monomer molecules join to form one large polymer molecule.

21. 21 Polymers • Polymers may have a wide range of properties. • The uses of a polymer depend on its properties.e.g. poly(ethene) for plastic bagsand poly(vinylchloride) for electrical wire insulation

22. 22 Biodegradable? • The disposal of non-biodegradable polymers causes environmental problems. • Microbes cannot break the polymer molecules down when they are buried in landfill sites. • Electrical wire insulation cannot be broken down either (phew).

23. 23 Ethanol from fermentation • Ethanol is a molecule which can be formed from renewable resources (fermentation of sugars). • Ethanol can be formed from non-renewable resources (ethene and steam).

24. 24 What are plant oils like? • Plant oils have a high energy content • Plant oils have high boiling points • Plant oils can be used in cooking. • This fried food has lots of extra energy that may lead to weight gain and heart problems in the long term.

25. 25 Margarine • Plant oils can be hardened into margarine, a solid fat. • The plant oil is made to react with hydrogen (hydrogenation). • This process uses a nickel catalyst that speeds up the rate of production.

26. 26 Extracting plant oils Plant oils can be extracted from plant material by: • pressing, • solvent extraction followed by • distillation, or steam distillation (for delicate oils).

27. 27 Emulsions, ice cream & mayo • Plant oils do not dissolve in water • They can be made into emulsions. • This involves the use of emulsifiers, for example, egg is used in the manufacture of mayonnaise from oil and vinegar

28. 28 The Earth is made of layers • The Earth has a layered structure. • Thick rocky crusts float on the mantle. • Its centre is the hot iron core.

29. 29 Tectonic plates • The crust is divided into tectonic plates. • Convections currents in the mantle cause the plates to move. • Earthquakes and volcanic eruptions occur at plate boundaries.

30. 30 Atmosphere • The Earth’s atmosphere has a stable composition. • 78% nitrogen21% oxygen, with small quantities of other gases including carbon dioxide

31. 31 Earth’s early atmosphere • The early atmosphere of the earth was mostly carbon dioxide and water vapour • There were small amounts of ammonia and methane.