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why do we need to know properties of materials
it describes how they behave
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what is melting point
the point at which a solid turns to liquid
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define tensile strength
how much a material can be stretched before breaking
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define compressive strength
how much a material can be compressed before breaking
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what is density
mass per unit of volume
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what is an incorrect result often referred to as
an outlier
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what do errors in measurements cause
variation in data
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give the properties of a metal
hard, shiny, malleable, good electrical conductors
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give the properties of ceramics
hard, strong
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give three natural materials that are taken from the earth
curde oil, coal, limestone
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what is a synthetic material
materials that are manufactured by chemical reactions using raw materials
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why have synthetic materials replaced some natural materials
natural materials are on a short supply, they can be specifically designed, cheaper and bigger quantities
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what is crude oil
a mixture of thousands of hydrocarbons
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what is a hydrocarbon
a compound made from hydrogen and carbon only
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how much of crude oil is used as fuel
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what is approx 3% of crude oil used for
synethise other chemicals
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how is crude oil separated
fractional distillation
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explain fractional distillation
the oil is heated so it turns into a gas, the tower is cooler at the top, gas molecules condense and liquids with similar boiling points collect together
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what happens when hydrocarbon chain length increases
force between the molecules increase
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why do some molecules have higher boiling points
they are larger,so need more energy to break them apart
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what is a polymer
a large molecule made from smaller molecules called monomers
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how is a polymer made
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How can polymer chains be altered
replacing hydrogen atoms with other atoms
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what does it mean if a polymer is high crystalline
high melting points, brittle
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what are plasticisers
small molecules, inserted into polymer chains to keep them apart, making them more flexible
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how can crystallinity be increased
removing branches and making the chains flatter
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how do nanoparticles occur
naturally (salt in Seaspray), accidentally (solid particles when fuels burn)
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what are nanoparticles
materials containing up to a thousand atoms
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what is nanotechnology
the use and control of very small structures
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why are some nanoparticles catalysts
they have a large surface area so more reactions can take place
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nanoparticles show different properties to larger particles of the same material, why
they have larger surface areas
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why is titanium oxide nanoparticles put into sunscreen
it absorbs UV light
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why are silver nanoparticles put into food containers, wound dressings and fibres
they kill bacteria
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what is a composite
materials like ceramics and metals mixed with nanoparticles
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what are the properties of composites
stronger, hardwearing
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what are graphite sheets
one-atom thick sheets, called graphene sheets
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what happens if silver nanoparticles get into sewage
it can kill the bacteria that is in there to clean the water
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what is one fear of nanoparticles in the air
if breathed in, they could cause lung or brain damage
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what do people want proof of hat nanotechnology will not do
cause health nd environmental risks
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why do people think nanoparticles cause no hard
they occur naturally (soot and volcanic dust)
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Other cards in this set

Card 2


what is melting point


the point at which a solid turns to liquid

Card 3


define tensile strength


Preview of the front of card 3

Card 4


define compressive strength


Preview of the front of card 4

Card 5


what is density


Preview of the front of card 5
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