Structure and properties

Metallic structure

metals consist of giant structures
metallic bonds involve 'free electrons' which are delocalised
the electrons are free to move around which is why they are good conductors of electricity
the electrons hold the atoms together in a regular structure and there are strong electrostatic attraction
they allow the layers of atoms to slide over each other, allowing atoms be bent and shaped
mix 2 pure metals together to create an alloy

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SIMPLE MOLECULER SUBSTANCES:

the atoms form very strong covalent bonds to form small molecules of several atoms
no electrical charge
forces of attraction are weak
low melting and boiling points
most of them are liquids and gases at room temperature
GIANT COVALENT SUBSTANCES:
no charges ions
don't conduct electricity
main examples are diamond and graphite, both made of carbon and silicon dioxide
DIAMOND:
no free electrons
no conductivity
4 covalent bonds
GRAPHITE:
good conductor of electricity and heat
3 covalent bonds

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bonds between molecule chains determine the properties of the plastic
weak forces: individual tangled chains of polymers, held together by weak intermolecular forces are free to slide over each other
strong forces: some plastics have strong intermolecular forces between the polymers chains called cross links

THERMOSOFTENING POLYMERS:

THERMOSETTING POLYMERS:

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nanoparticles include fullerenes
nanoparticles behave differently from the materials they are made from
nanoparticles have a huge surface area to volume ratio
they could be uses to make stronger, lighter building materials
nanotubes conduct electricity
smart materials behave differently depending on the conditions
nitionol is used for dental braces and when it's cool, you can bend and twist it

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