17/04/2015 Properties of materials Vulcanised rubbers High tensile strength Hard Flexible
17/04/2015 C2.2 Crude Oil
17/04/2015 Using Different Materials We use a variety of materials from a variety of different places: Cotton from plants Silk from silkworms Wood and paper from trees These are all “natural” materials – we can also use synthetic (man-made) ones like plastics – these are often made from materials from within the Earth like crude oil.
17/04/2015 C2.4 Nanotechnology
17/04/2015 Chemical formulae The chemical formulae of a molecule or compound is simply a way of showing the ratio of atoms in it. For example… NaCl = sodium chloride (NaCl) KI = potassium iodide (KI) KN OOO = potassium nitrate (KNO 3 )
17/04/2015 Chemical formulae Try drawing these: 1)Water H 2 O 2)Carbon dioxide CO 2 3)Calcium sulphate CaSO 4 4)Magnesium hydroxide Mg(OH) 2
17/04/2015 Simple chemical reactions Mg O H Cl Mg Cl H H O H Magnesium+Copper sulphate Mg O O Cu O O S Mg O O O O S Magnesium sulphate Copper + H2OH2OMgO+ WaterMagnesium oxide +Hydrochloric acid Magnesium chloride + 2HCl MgCl 2 + MgSO 4 Mg+CuSO 4 Cu + Notice that the number of atoms on each side of the equation is the same!
17/04/2015 Hydrocarbons and crude oil Increasing length Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples: Ethane C C H H H HH H Butane CC H H H HH H C C H H H H These different “lengths” are called “_______” and most of them are used as _____. Some are used to make materials such as _______. Longer chains have higher _____ points. Words – boiling, fractions, plastics, fuels
17/04/2015 Fractional distillation Crude oil can be separated by fractional distillation. The oil is evaporated and the hydrocarbon chains of different lengths condense at different temperatures: Fractions with low boiling points condense at the top Fractions with high boiling points condense at the bottom
17/04/2015 Forces between molecules Weak force of interaction here Longer molecules = stronger force of attraction, leading to higher boiling points due to the molecules needing more energy to “pull” them away from each other.
17/04/2015 Polymers CC H H H H Ethene Here’s ethene. Ethene is called a MONOMER because it is just one small molecule. We can use ethene to make plastics… Step 1: Break the double bond Step 2: Add the molecules together: This molecule is called POLYETHENE (i.e. polythene), and the process that made it is called POLYMERISATION
17/04/2015 C2.3 Molecular Structure
17/04/2015 Uses of addition polymers Poly(ethene)Poly(propene) Poly(chloroethene), PVCPoly(styrene)
17/04/2015 Structure of Plastics 1) Some plastics have ____ intermolecular forces between each molecule – these have __ melting points and can be ________ easily 2) Some plastics have _____ forces between each molecule. These have ____ melting points and are ____. Words – high, low, strong, weak, stretched, rigid
17/04/2015 Forces between molecules As we’ve already said, longer molecules have stronger forces of attraction between them. This tends to lead to longer chain plastics being: 1)Stronger 2)Stiffer 3)Harder 4)More difficult to melt (i.e. higher melting point)
17/04/2015 Modifying Plastics Polymers can be modified in a number of ways: 1)Increasing the chain length...making it stronger 2) Crosslinking...making it harder 3) Plasticizing...making it softer and more flexible 4) Packing more closely (a crystalline polymer)...making it stronger and more dense
17/04/2015 Nanotechnology Task: To find out what nanotechnology is and what it is used for 1)What is nanotechnology? 2)Define the terms nanoparticle and nanocomposite 3)Gives some examples of its uses 4)Describe some of the future uses of this technology 5)Describe some of the ethical concerns over this technology
17/04/2015 Nanotechnology Nanotechnology is a new branch of science that refers to structures built from a few hundred atoms and are nm big. They show different properties to the same materials in bulk, partly because they also have a large surface area to volume ratio and their properties could lead to new developments in computers, building materials etc. Definition:
17/04/2015 How nanoparticles are formed Nanoparticles can be formed by a number of methods: They can occur naturally in sea spray They can also be formed during combustion Or they can be formed by grinding down materials
17/04/2015 Two examples of nanotechnology The “Nano Carbon Pro” tennis racket uses nanoparticles to increase its strength. Silver nanoparticles can be used to give fibres antibacterial properties – look at what they do to e-coli bacteria: Normal e-coli E-coli affected by silver nanoparticles
17/04/2015 Nanoscience and health Nanoparticles are obviously very small and, as we have said, have a large surface area to volume ratio. This makes them useful but can also make them dangerous. Nanoparticles could easily pass through a cell membrane: How do these health concerns affect the development of nanotechnology? I’m going to die…
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