Giant Covalent Bonding

Giant Covalent BondingAllotropic forms of carbonFun factsan element is said to exhibit allotropy ifit occurs in 2 or more formsDiamondevery carbon atom is bonded to4 other crabon atoms by strong covalent bondsgiant covalent structuremade up of only carbon atomsHigh melting pointlarge amount of energy required tobreak the strong covalent bonds between carbon atomsin the giant molecular structurenon - conductor of electricityno delocalised electrons as all valenceelectrons of each carbon atoms are usedfor covalent tbondingGraphitefound in sandconsists of seperate layers of carbon atomscarbon atoms are arranged in regular hexagonsin flat parallel layerscarbon forms strong covalent bonds with3 other carbon atoms forms rings of 6 carbon atoms which are joined together to for 2 - dimensional layersno strong bonding in between layersthey are easily seperable from each otherheld together by weak forces of attractionso the layers slide overeach other easily whena force is appliedaccounts for softness andlubricating power of graphitephysical propertieshigh melting and boiling pointsforces of attraction between layers are weakbut a lot of energy is still needed tobreak the strong covalent bonds between carbon atoms within layersthis can cause a change of stateGood conductor of electricitySoft and slipperyeach carbon atom has 1 valence electronthat isn't used to form covalent bondsdelocalised electrons move freelyalong layers from one C.A. to anotherwhen graphite is connected to a circuitthis causes an electric current to flow,causing graphite to conduct electricitywhen a force is appliedweak forces of attraction betweenthe layers of carbon atoms are easily overcomeso layers can easily slide over one anotherSilicon dioxidegiant covalent structureeach silicon atom is bondedto 4 oxygen atomseach oxygen atom is bonded to 2 oxygen atomsatoms are held together by strong covalent bondshigh melting pointsstructure similar to diamondsimilar physical propertiesused to produce glassFullerenea molecule made up of carbon atomsarranged in the form of a hollow spherecylindercalled 'buckyballs'called 'carbon nanotubes'amorphous forms of carbonmost reactive form of carbondoes not have any crystalline structureburns relatively easily in airserving as a fuelhas structural features of graphitehas sheets and layersatomic structure is irregular