structure and properties 0.0 / 5 ? ChemistryPolymersNanoscienceStructure and bondingGCSEAQA Created by: bxthanyCreated on: 26-04-14 16:23 what state are giant structures in at room temperature? solid (a lot of energy is needed to overcome ionic bonds) 1 of 27 do ionic compounds have high melting/boiling points or low ones? ionic compounds have high melting points and high boiling points 2 of 27 can giant ionic structures conduct electricity? only when melted or dissolved in water as ions are free to move and carry charge through the liquid 3 of 27 why do some ionic solids dissolve in water? because water molecules can split up the lattice 4 of 27 why can giant ionic structures not conduct electricity when solid? because ions can only vibrate about in fixed positions 5 of 27 what are atoms in a molecule held together by? strong covalent bonds 6 of 27 simple molecules have little attraction for each other, why? as the strong covalent bonds act only between atoms within the molecule 7 of 27 why do simple molecules have low boiling/melting points? they have weak inter molecular forces between the simple molecules 8 of 27 do simple molecules conduct electricity and why? no they do not as molecules have no overall charge so they cannot carry electrical charge 9 of 27 why might large molecules be liquid at room temperature? they have stronger attractions 10 of 27 what happens when we bend/shape metals? the layers of atoms in the giant metallic structure slide over each other 11 of 27 giant metallic structures can move without breaking, how is this useful? they are good for making wires, rods and sheet materials 12 of 27 what are alloys? mixtures of metals (harder than pure metals because layers in structure are distorted) 13 of 27 what are shape memory alloys? alloys that return to their original shape when heated 14 of 27 what do delocalised electrons in metals allow metals to do? conduct heat and electricity 15 of 27 why do covalently bonded substances with giant structures have high melting points? because it takes an enormous amount of energy to break down the lattice 16 of 27 why is diamond hard/transparent? as it is a form of carbon whose atoms each form four covalent bonds 17 of 27 why is graphite slippery/grey? it is a form of carbon where carbon atoms form layers that have no covalent bonds so they slide over each other 18 of 27 why can graphite conduct electricity? because if its delocalised electrons in its structure 19 of 27 what are fullerenes? large molecules from hexagonal rings of carbon atoms 20 of 27 what do the properties of a polymer depend on? monomers used to make it and conditions used during reactions 21 of 27 what type of polyethene has a high softening temperature and is stronger? high density polyethene 22 of 27 what do thermosoftening polymers do when heated? soften/melt easily 23 of 27 what is nanoscience? study of small particles that are between 1 and 100 nanometres in size 24 of 27 how long is a nanometre? one billionth of a metre 25 of 27 how does nanotechnology use nanoparticles? as highly selective sensors, efficient catalysts and cosmetics (sun screen) 26 of 27 why does more research need to be done before nanoparticles are used in more materials? there is a high risk of them getting into the air and bodies 27 of 27
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