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| Frage | Antworten |
| why do simple molecules not conduct electricity? | the molecules do not have an overall electric charge |
| why do giant ionic lattices have high melting and boiling points? | large amounts of energy are needed to break the many strong bonds |
| what are alloys and what are the differences between the structure of an alloy and a pure metal? | materials made from 2 or more types of metals. The different sized atoms of the metals distort the layers in the structure making it more difficult for them to slide over one another |
| what is special about shape memory alloys? give an example | they can return to their original shape after being deformed eg) Nitinol used in dental braces |
| what do the properties of polymers depend upon? | what they are made from and the conditions under which they were made |
| why are Low density and High density polythene different? | they were produced using different catalysts and reaction conditions |
| what are plastics that have individual tangled polymer chains? | thermosoftening |
| what are the properties of thermosetting plastics? | they consist of polymer chains with crosslinks betwen them so they do not melt when they are heated |
| why do thermosoftening polymers melt easily? | the chains of polymers are held together by weak intermolecular forces. The forces between the chains are really easy to overcome so its easy to melt the plastic |
| what size of structure does nano science refer to ? | structures that are 1-100nanometers |
| why may nano-particles have different properties to the same materials in bulk? | they have a higher surface area to volume ratio |
| when can ionic compounds conduct electricity and why? | when molten or dissolved in water because the ions are free to move and carry the current |
| in diamond, how many bonds does each carbon atom form, what type of bond? | each carbon atom forms 4 covalent bonds in a giant structure |
| in graphite, each carbon atom bonds to how may others? | each carbon atom covalently bonds to three others forming layers |
| why can graphite conduct heat and electricity? | like metals, graphite has delocalised electrons which can carry current |
| how strong are the forces between the layers in graphite and what property does this give graphite? | the intermolecular forces between the layers are weak and the layers slide over each other because there are no covalent bonds between the layers so graphite is soft and slippery |
| what can carbon also form with different numbers of carbon atoms? | fullerenes |
| what are the uses of fullerenes? (4) | -drug delivery into the body -lubricants -catalysts -in nanotubes for reinforcing materials |
| why can metals conduct heat and electricity? | the delocalised electrons in their structure carry charge and move throughout the material |
| why can metals be bent and shaped? | the layers of atoms in metals are able to slide over one another |
| Do substances that consist of simple molecules have low or high melting/boiling points? | low |
| do substances that have simple molecules have weak or strong inter molecular forces? | weak |
| incomparision to intermolecular forces, are the covalent bonds strong or weak | strong |
| which forces are overcome when a simple molecular substance melts or boils? | the intermolecular forces.. the covalent bonds are still intact |
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