1 elements and their atoms each element of the periodic table is built from one type of atom atoms...

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 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 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 Cement and concrete

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

form concrete.

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 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 The ‘Lime’ cycle

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 Transition elements

• Transition metals are hard, strong and have coloured compounds

10 Alloys

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

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 Extracting metals from their ores

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

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 What is crude oil?

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

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 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 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 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 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. Alkenes decolourise bromine water.

20 Making polymers

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

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 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 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 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 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 Extracting plant oils

Plant oils can be extracted from plant material by:1)pressing, 2)solvent extraction

followed by3)distillation, or steam

distillation (for delicate oils).

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 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 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 Atmosphere

• The Earth’s atmosphere has a stable composition.• 78% nitrogen

21% oxygen, with small quantities of other gases including carbon dioxide

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.