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22 Cards in this Set
- Front
- Back
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What are the materials that we use? |
Chemicals or mixtures of chemicals E.g. metals, ceramics and polymers |
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How can natural materials be obtained and give examples? |
Can be obtained or made from living things E.g. cotton, paper, silk and wool |
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What are alternatives to materials made from living things? |
Synthetic materials |
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How can synthetic materials be made? |
Raw materials from the earth's crust can be used to make them |
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What is conservation of energy? Give an example |
Matter cannot be created or destroyed For example in a chemical reaction the number of atoms in an element must be the same in the products and the reactants |
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What are hydrocarbons? Give an example |
Long chain molecules of varying lengths made from carbon and hydrogen atoms only For example crude oil consists mainly of hydrocarbons |
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How much crude oil is used for chemical synthesis? |
Only a small percentage, most is used as fuels |
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How does the petrochemical industry refine crude oil? |
By fractional distillation Hydrocarbons are separated into fractions of boiling points to produce fuels, lubricants and raw materials for chemical synthesis |
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What is polymerisation? |
When small molecules known as monomers join together to make very long molecules called polymers |
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What 2 materials that because of their superior properties have replaces materials in the past? |
uPVC has replaced wood in window frames as it doesn't rot Gore tex doesn't allow water molecules through but allows sweat out |
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Is it possible to produce a wide range of different polymers? |
Yes, they all have properties that make them suited to a particular use |
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What do the properties of polymers depend on? |
How their molecules are arranged and held together |
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What are the 4 modifications you can make to polymers? |
Increased chain length Cross linking Increased ctystallinity Plasticisers |
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How does increased chain length change the properties of polymers? |
It increases their forces of attraction They make the material stronger and less flexible |
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How does cross linking affect the properties of polymers? |
It makes the material tougher and less flexible |
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How do plasticisers change the properties of polymers? |
They push the polymer molecules slightly further apart, weakening the forces between them and making the material softer and more flexible. |
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How does increasing crystallinity change the polymers properties? |
The material has a higher density than LDPE ( low density polyethene) The forces of attraction between polymer molecules are strongThe material is stronger, and has a higher melting point |
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What does nanotechnology involve? |
Structures that are the same size as some molecules |
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What is nanotechnology? |
The use and control of structures that are very small (1 to 100 nanometers in size) |
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Can nanoparticles naturally occur? |
Yes, for example in seaspray |
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Do nanoparticles show different properties compared to larger particles of the same material? Explain why |
Yes, because of the much larger surface area of nanoparticles compared to their volume |
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Nanoparticles can be used to modify the properties of materials, give examples |
The use of silver nanoparticles to give fibres antibacterial properties Adding nanoparticles to plastics for sports equipment to make them stromger |
