1. a) good b) poor c) small molecules d) ionic e) poor f) covalent g) giant

2. very hard melts at 1610 C does not conduct electricity when molten Many molecular solids are crystalline or insoluble in water covalent Si and O are both non metals and need to gain electrons

3. Good conductor of heat Is hard but not brittle High melting point Conductor of electricity Conductor of heat Layers of atoms slide over each other Atoms stay bonded because of de-localised electrons

4. Structures / particles of about 1nm may contain a few hundred atoms Have different properties to materials in bulk Can make new catalysts and coatings or new devices Much larger surface area Increases rate of reaction

5. Increased sales of mobile phones Uses less raw material due to small size / Could warn fireman of dangerously hot temperatures

6. C: carbon atoms H: hydrogen atoms Covalent bond Particles are uncharged / there are no ions Its made of molecules / covalently bonded Molecules have enough energy to move apart / escape from the liquid / overcome intermolecular forces Covalent bonds are not broken