polymer Flashcards
Why can metals conduct electricity?
They have delocalised electrons, which are free to move around the whole structure, and carry an electrical charge
Why are metals malleable?
They are arranged in layers which can slide over each other
Why do they have high melting and boiling points?
They have lots of strong forces of attraction which need a lot of energy to overcome
what are the properties of metals ?
Strong High melting point Shiny Good electrical and thermal conductors Flexible
what are the properties of a non-metals?
Brittle
Low melting point
Dull
Poor electrical and thermal conductors
Why are metals used in pans?
They conduct heat
Why are they used in buildings?
They are strong
Why are they used in wires?
They are ductile and conduct electricity
Define an alloy
A metal mixed with another element
List 3 natural and 3 synthetic materials
Natural materials include wood, water, air, sand etc
Synthetic materials include glass, paper, plastics
Synthetic materials are man made
Steel is used in building because…
they are strong and hard
Copper is used in electrical items because…
they are good conductor of electricity
China is used for tea pots because…
they are good thermal insulator
2 strong materials are…
Steel, iron (metals)
2 thermal insulators are…
Plastic, rubber
2 conductors (thermal and electrical) are…
Iron, aluminium
Describe 6 things a bar chart needs
X axis labels Y axis labels Suitable scale Gaps between bars Bars equal width Bars drawn to the correct height
Explain why substances are brittle
Atoms are in a rigid structure and can’t move past each other
Explain why substances are hard
Lots of strong bonds in a giant lattice
Explain why substances have high melting points
Lots of strong bonds which require a lot of thermal energy to break
Explain why substances can conduct electricity
Delocalised electrons which are free to move around the structure and carry a charge
Describe and explain the conditions needed to form large crystals in ceramic materials.
Allowing them to cool slowly, which means there is enough time for the lattice structure to form
Define polymer
Lots of small molecules joined together in a long chain.
Give 2 examples of polymers
PVC, polystyrene
How are polymers formed?
From monomers, repeat units, joined together
Plastic means:
It will not return to its original shape when stretched
Elastic means:
It will return to its original shape when stretched
A composite material is
two or more materials combined with some of the properties of each
Give 2 examples of composites
Paper
Concrete
What 4 things do you need to make concrete?
Cement
Sand
Aggregate
Water
Define thermal decomposition:
Where a compound is broken down into simpler substances using heat energy
What is the word equation for thermal decomposition of calcium carbonate?
Calcium carbonate → Calcium oxide + carbon dioxide
Give 3 reasons for recycling plastics:
To preserve natural resources
To save energy
Some substances are not biodegradable (they are not broken down by living organisms)
How do you recycle metals?
Separate them then melt them
How do you recycle glass?
Sort by colour, crush and melt them
How do you recycle plastic?
Melt and mould into new materials
State and explain how the properties of vulcanised rubber differ from natural rubber
Cross links increases its melting point and makes it harder - more bonds to overcome.
Cross links increases elasticity - layers can return to their original positions
