Chapter 1: Materials in Our World Flashcards
What is a material
a material is a substance used to make objects e.g wood is used to make houses.
- substances that don’t count is HCL or CO2 because they aren’t used to make objects
What are elements
elements are substances made of atoms containing the same amount of protons / atomic number
What are compounds
compounds are pure substances made of more than one type of atom, containing more than one element in fixed proportions
What is a pure substance
a pure substance is a sample of matter that only contains one type of compound or atom e.g pure gold, pure water, pure sodium chloride
What is an alloy and why are they used
a mixture of a two metals or a metal and a small amount of a non metal
iron is naturally soft and corrodes easily, but when alloyed with carbon it is much stronger and corrosion resistant
what is a polymer and why are they used
a molecular structure composed of many repeating smaller units bonded together
e.g plastics and latex are polymers and are used due to their low density, electrical insulation and corrosion resistance
compatibility with human tissue
What is a ceramic and why are they used explain crystalline vs amorphous
inorganic non metallic solid. metal, non metal and metalloid substances bonded together covalently
crystalline - highly ordered
amorphous - highly irregular
e.g porcelain, silicon and carbide used for high compressive strength, temperature resistance, insulating, semi conductor or super conductor
What is a composite material
a combination of two or more distinct materials with significantly different physical and chemical properties
e.g reinforced concrete is concrete containing steel bars which supplements the concretes relatively low tensile strength while keeping the compressive strength of concrete
What is nanoscale and how big is a nanometre
structures between 1-100 nanometres are considered nanoscale
a nanometre is 1 billionth of a metre (10^-9m)
what is top-down fabrication + pros and cons (1 each)
material starts bigger than desired
material is selectively removed or size is reduced until desired shape is achieved
e.g computer chips and sunscreen
cheap and mass produced. limited to simple structures
what is bottom-up fabrication + pros and cons (1 each)
physically building or growing the material atom by atom
self assembling nanomaterials
complicated structures but cannot be mass produced
what is a nanoparticle + examples
spherical particles with diameter from 1-100nm
different properties form their bulk forms due higher surface area to volume ratios
used in stained glass or ceramics to obtain different colours at different sizes
What is sieving
separation by particle size
separating solids of different sizes using a sieve which only allows particles smaller than the holes to pass
What is filtration
separation by particle size
used to separate solids from a liquid or gas
pool filters, coffee filters
explain filtrate and residue
the filtrate is the liquid that collects in the flask
the residue is the solids collected in the filter paper
what is vacuum filtration
Buchner funnel is ceramic and has holes at the bottom and filter paper on top
the liquid flows through the funnel as the vacuum connected to the flask pulls
dries the filtrate quicker and is faster than gravitational filtration
what is sedimentation
separation by density
sedimentation is when you let a mixture of solids and liquids sit
this allows gravity to pull the denser objects to the bottom and then the finer ones rest on top
water treatment plants use this as a cheap way to separate large volumes of solids and liquids
what is decantation
after the sediment has settled in the liquid you can pour out the liquid into another container
how does liquids being immiscible allow them to be separated in a separation funnel
separation by density
immiscible is when two liquids cant mix
so when the mixture has two liquids that are immiscible and different densities and is allowed to sit the liquids will separate themselves in layers
the flask can then be opened allowing the denser liquid to flow out first
e.g oil and water are immiscible
what is centrifugation
separation by density
spinning a mixture very quickly (20000rpm) separates the less dense particles from the more dense through centrifugal force
speeded up version of sedimentation
what is evaporation
separation by boiling point
used when solids dissolve into a liquid
the solution is boiled so that the liquid evaporates and the solid is left behind
explain solute vs solvent
solute - dissolved solid
solvent - the liquid
explain what fractional distillation is
same as regular distillation but has a fractioning column with high surface area beads
allows the more volatile component to exit as vapour at the top and the less volatile to condense back into the distillation flask
what is electrostatic separation
separation by electric charge
objects with opposite charge attract (electrostatic attraction)
therefore electrostatic attraction can be used to separate charged particles from uncharged
electrostatic filters can separate smoke particles from waste gases by passing the smoke through an negatively charged grid so that the smoke particles have a negative charge
they can then by attracted by the positively charged electrodes to collect the smoke particles
