C3

• Diamond is a form of carbon with a giant covalent structure
• DIAMOND PROPERTIES: very hard, high melting point , doesn't conduct electricity
• In diamond, every carbon atom forms strong covalent bonds with 4 other carbon atoms
• Diamond is used in jewellry and for coating blades in cutting tools
• Graphene is a single layer of graphite with hexagonal rings, one carbon atom thick
• GRAPHENE PROPERTIES: good conductor of electricity, has very low density and strong for its mass
• GRAPHENE USES: electronics and composites
• In graphite, each carbon atom forms 3 covalent bonds with other carbon atoms that form hexagonal rings that are arranged in giant layers
• In graphite, between the layers there are no covalent bonds, only weak intermolecular forces so the layers can slide over each other quite easily, making it soft and slippery
• WHY CAN GRAPHITE CONDUCT ELECTRICITY?

  one electron from each carbon atom is delocalised like electrons, the delocalised electrons can conduct heat and electricity
• Atoms in a pure metal are arranged in closely packed layers in giant metallic structure. Layers of atoms are able to slide over each other so they can be bent and shaped
• Alloys are mixtures of metals or metals with other elements.
• In alloys, the different size atoms distort the regular pattern of atom in layers making it more difficult for layers of atoms to slide over each other so alloys are harder than pure metal
• Metals have high melting and boiling points as in giant structures electrostatic forces of attraction between positive metal and delocalised electrons extend in all directions so lot of energy is required to break down lattice
• Metals are good conductors of thermal energy and electricity. The electrical charge and thermal energy are transferred quickly through structure by free-moving delocalised electrons
• Intermolecular forces increase as size of molecule increases so larger molecules will have higher melting and boiling points
• Ionic compounds have giant structures in which many strong electrostatic forces operate in all directions holding oppositely charged ions together
• Ionic compounds at room temperature are solid because it takes a lot of energy to overcome strong electrostatic forces
• In ionic compounds, the ions are free to move so they can carry electrical charges so when ionic compounds are in molten state they can conduct electricity
• Some ionic solid dissolve in water because water molecules can split up lattice, ions are free to move in solutions so they can conduct electricity
• Atoms of non-metals need to gain electrons and can do this by sharing electrons with other atoms, each shared pair of electrons strongly attracts the two atoms, forming a covalent bond, these substances are molecules
• Covalent bond only acts between two atoms it bonds together and so many covalently bonded structures consist of small molecules, sometimes a molecule can contain double or triple covalent bonds
• Carbon nanotubes are cylindrical fullerenes and have delocalised electrons giving high electrical industry
• CARBON NANOTUBES PROPERTIES: high length to diameter ratio, high tensile strength which is useful to reinforce composite materials for tennis rackets
• In fullerenes, carbon atoms join together to make large hollow shapes based on hexagonal rings of carbon atoms
• Fullerenes can have rings of 5 or 7 carbon atoms
• First fullerene to be discovered was Buckminister fullerene (C60) which had 60 carbon atoms and had a spherical shape.
• Fullerenes are used for drug delivery in body, lubricants and catalysts
• Nanoparticles have high surface area to volume ration making them more reactive than normal particles
• Nanoparticles are used in cosmetics, for deodrants and face creams as they absorb deeper into face and in sun creams as they are more effective at blocking sun rays
• Nanoparticles are used in medicine, carbon nanocages deliver drugs in body and in wound dressings of silver nanoparticles to protect against bacteria
• Nanoparticles are used in computers as nanowires give improved memory capacities and speeds
• Polymers have large molecules made up of many small molecules that covalently bond to each other to form long chains