1
Q
What are Materials?
A
- Substances used to make objects
- Can be a mixture of substances or pure elements/compounds
2
Q
Examples of materials
A
- Wood
- Nylon
- Paper
3
Q
Substances not considered materials
A
Chemicals such as hydrochloric acid, chlorophyl and carbon dioxide
4
Q
Definition: Element
A
Pure substances that are made up of just one type of atom
5
Q
Example of an element
A
- Carbon
- Gold
- Silver
6
Q
What are Compounds?
A
- Pure substances made up of more than one type of atom
- They consist of more than one type of element in fixed proportions
7
Q
Examples of compounds
A
- SiO2 (silica)
- H2O (water)
- C6 H12 O6 (glucose)
8
Q
Chemical/physical properties that influence a materials use
A
- Colour
- Hardness
- Melting point
- Boiling point
- Conduction of electricity
- Conduction of heat
- Ability to react with other chemicals
9
Q
Can properties of elements/compounds be altered
A
Thay cannot be as they are pure substances
10
Q
How are the properties of elements/compounds determined
A
Determined by the arrangement of their atoms molecules and are distinct and measurable for given arrangement of atoms and molecules
11
Q
Can properties of mixtures change
A
Can be changed depending on the concentration of each element in the mixture which makes them very useful materials
12
Q
What is Mixture?
A
A physical combination of two or more substances that do not change their chemical makeup or form or break bonds with each other
13
Q
What are Metals properties?
A
- High tensile strength
- Ductility
- Malleability
- Shiny luster
- High melting point
- Thermal conductivity
- Electrical conductivity
14
Q
Categories of materials
A
- Metals
- Polymers
- Ceramics
15
Q
What is Metals?
A
- Valuable materials due to their properties
- 80% of all known elements
- Found in elemental metallic forms and as compounds known as minerals
16
Q
How can you improve a metals weak point
A
Use an alloy of the metal
17
Q
What are Alloy?
A
A mixture of a metal with other metals or small amounts of non-metals
18
Q
What are Polymers?
A
- A material with a molecular structure that is composed of many repeating smaller units bonded together
- Includes plastics, nylon and rubbers
- Natural and synthetic polymers
19
Q
Properties of Polymers
A
- Less dense
- Corrosion resistant
- Electrical resistance
- Polymers of biological nature offer good compatibility with human skin
20
Q
What are Ceramics?
A
- An inorganic, non-metallic solid
- Natural and synthetic ceramics
- The degree of order within ceramic materials can range from highly ordered to highly irregular
21
Q
Example of natural polymers
A
- Wool
- Paper
- Silk
22
Q
Example of synthetic polymers
A
Polystyrene
23
Q
Example of natural ceramics
A
Kaolinite (used to make porcelain)
24
Q
Example of synthetic ceramics
A
Silicon carbide (used as an abrasive)
25
What is a structure that is highly ordered called?
Crystalline
26
Highly irregular
Amorphous
27
What are Composite materials?
- A combination of two or more distinct materials with distinctly different physical or chemical properties
- Has properties that are unobtainable by using an individual material
28
What are Nanotechnology?
The science that investigates the design, properties and application of materials on the nanoscale
29
What is a Nanoscale?
- Structures between 1 and 100 nanometers across
- 1 nanometre is a billionth of a metre
30
What are Nanomaterials?
Substances both natural and synthetic that are composed of single units that exist on the nanoscale
31
Example of nanomaterials
Fullerenes (family of carbon molecules)
32
Fullerenes
Three-dimensional structures formed by a network of carbon atoms
33
Which fullerene promises the most opportunities
The cylindrical tube known as the carbon nanotube
34
Carbon nanotubes
Formed from a layer of two-dimensional carbon atoms arranged in hexagons known as graphene
35
Carbon nanotubes properties
- Finds a use as a reinforcement in composite materials
- Interesting electrical properties
- Exceptional strength
- Stiff
- The base of all superconductor research
36
The two ways materials on the nanoscale can be fabricated
- Bottom-up fabrication
- Top-down fabrication
37
Top-down fabrication
Starts with a material of a much larger scale than desired which is then selectively removed or the size of the material is gradually reduced through grinding until the required shape and size is formed
38
Examples of top-down fabrication
- Computer chips
- Sunscreen
39
Advantages of top-down fabrication
Large quantities of material can be produced cheaply and the product demonstrates good levels of uniformity
40
Disadvantages of top-down fabrication
Limited to relatively simple structures and by the scale of the tools used to remove the material from the starting medium
41
Bottom-up fabrication
Physically growing or building the required material atom by atom or molecule by molecule until the required shape and size is formed
42
Advantages of bottom-up fabrication
Can be used for far more complicated structures due to the ability of being able to manipulate atoms/molecules at the nanoscale
43
Disadvantages of bottom-up fabrication
They do not scale up to commercial levels efficiently and thus are currently only economical for research and niche applications
44
Nanoparticles
- A specific type of nanomaterial
- Usually spherical with diameters of 1-100nm
- In this size the properties of materials begin to change from those normally observed for bulk material due to greater contribution of Quantum effects
- Potential in medicine, physics, optics and electronics
45
Separation techniques using either physical or chemical properties
- Particle size
- pH
- Density
- Solubility
- Electric charge
46
Separation through particle size
- Sieving
- Filtration (vacuum and gravitational)
47
Sieving
- Passing a mixture through a mesh, particles smaller than the holes in the mesh will pash through leaving larger ones behind
- Separate a mixture of solids with different particle size
48
Filtration
- Separate solid particles from liquid or gas
- Filter paper seperates liquid from solids
49
Gravitational filtration
- Using the weight of the mixture to push the mixture through the filter paper
- Purified liquid = filtrate
- Solid = residue
50
Vacuum filtration
- Faster than gravitational and helps dry the residue faster
- Rubber seal and side arm on the conical flask
51
Separation by density
- Sedimentation and decantation
- Separation funnels
- Centrifugation
52
Sedimentation and decantation
- Sedimentation = settling (form of gravitational separation)
- The liquid can then be separated from the sediment very carefully, pouring the liquid into another container (decantation)
- Cheap method, large volumes
53
Seperation funnels
- If two different liquids have different densities and are immiscible they can be separated by a separation funnel
- Liquid- liquid extraction
54
Centrifugation
Spinning a mixture rapidly- speeds up the sedimentation process and extracts finer particles that may not settle naturally
55
Seperation by boling point
- Evaporation
- Distillation
- Fractional distillation
56
Evaporation
The liquid solvent is boiled off to reveal the solid solute
57
Distillation
Similar to evaporation but uses an apparatus to recover the evaporated liquid
58
Fractional distillation
- Separate miscible liquids when their boiling points are slightly different
- Same as distillation flask but with an extra column which allows for increased contact between rising vapour and falling condensate
59
Seperation by electric charge
Chromatography
60
Chromatography
Separates liquids based on their differing affinity for various materials present in the chromatography apparatus
Chemistry
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