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polymers & giant covalent structures& allotropes of carbon &…
polymers & giant covalent structures& allotropes of carbon & metallic bonding
polymers are long chains of repeating units
2) the intermolecular force between polymer molecules are large than between simple covalent molecules so more energy is needed to break hem this means most polymers are solid at room temperature
3) the intermolecular forces are still weaker than ionic or covalent bonds so they generally have lower boiling points than ionic or giant molecular compounds
1) in a polymer lots of small units are linked together to form a long molecule that has repeating sections all the atoms in a polymer are joined by strong covalent bonds
giant covalent bonding
2) they have very high melting and boiling points as lots of energy is needed to break the covalent bonds between the atoms
3) they don't contain charged particles so they don't conduct electricity not even when molten
1) in giant covalent structure all the atoms are bonded to each other by strong covalent bonds
4) the main example are diamond and graphite which are both made from carbon atoms only and silicon dioxide
diamond is very hard
1) diamond has a giant covalent bond structure made up of carbon atoms that each form four covalent bonds this makes diamonds really hard
2) those strong covalent bonds take a lot of energy to break and give diamond a very high melting point
3) it doesn't conduct electricity because it has no free electrons or ions
graphite contains sheets of hexagons
2) there arnt any covalent bonds between the layers they are only held together weakly so they are free to move over each other this makes graphite soft and a slippery so its ideal as a lubricating material.
3) graphite got a high melting point the covalent bonds in the layers need loads of energy to break
1) in graphite each carbon atom only forms three covalent bonds creating sheets of carbon atoms arranged in hexagons
4) only three out of each carbons four outer electrons are used in bonds so each carbon atom has one electron that's delocalised free and can move so graphite conducts electricity and thermal energy
graphene is one layer of graphite
3)the network of covalent bond makes it very strong its also incredibly light so can be added to composite material to improve their strength without adding much weigh
2)the sheet is just one atom thick making it a two dimensional compound
4) like graphite it contains delocalised electrons so can conduct electricity through the whole structure this means it has the potential to be used in electricity
1) graphene is a sheet of carbon atoms joined together in hexagons
fullerenes form spheres and tubes
3) fullerenes can be used to cage other molecules the fullerene structure forms around another atom or molecules which is then trapped inside this could used to deliver a drug into the body
4)fullerenes have a huge surface area so they could help make great individual catalyst molecules could be attached to the fullerenes .
2) they are mainly made up of carbon atoms arranged in hexagons but can also contain pentagons or heptagons
5) fullerenes also makes great lubricants
1) fullerens can form nanotubes tiny carbon cylinders
2) the ratio between th length and the diameter of nanotubes is very high
3) nanotubes can conduct both electricity and thermal energy
4) they also have a high tensile strength
5) technology that uses very small particles such as nanotubes is called nanotechnology nanotubes can be used in electronics or to strengthen materials
1) fullerenes are molecules of carbon shaped like closed tubes or hollow balls
metallic bonding involves delocalised electrons
3) these forces of attraction hold the atoms together in a regular structure and are known as metallic bonding metallic bonding is very strong
4) substances that are held together by metallic bonding include metallic elements and alloys
2) the electrons in the outer shell of the metal atoms are delocalised there are strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons
5) its the delocalised electrons in the metallic bonds which produce all the properties of metals
1) metals also consist of a giant structure
metallic bonding
most metals are solids at room temperature
the electrostatic forces between the metal atoms and the delocalised sea of electrons are very strong needs lots of energy to be broken this means that most compounds with metallic bonds have very high melting and boiling points so they are generally solid art room temperature
most metals are malleable
the layers of atoms in a metal can slide over each other making metals malleable this means that they can be bent or hammered or rolled into flat sheets
alloys are harder than pure metals
1) pure metals often arnt quite right for certain jobs they are often too soft when they are pure so are mixed with other elements to make them harder
2) different elements have different sized atoms so when another elements is mixed with a pure metal the new metal atoms will distort
metals are good conductors of electricity and heat
the delocalised electrons carry electrical current and thermal energy through the whole structure so metals are good conductors of electricity and heat