60055
| Questão | Responda |
| what does the mass number tell you? | the number of protons and neutrons |
| what does the atomic number tell you? | the number of protons |
| what is a compound? | atoms of 2 or more elements chemically joined together |
| what is an isotope? | different atomic forms of the same element, which have the same number of protons but different number of neutrons |
| does the mass number or the atomic number change with isotopes? | the mass number |
| give 2 properties of ionic compounds | high m.p and conduct when molten |
| give 2 properties of simple molecular substances | weak intermolecular forces and don't conduct |
| give 3 examples of giant covalent structures | diamond, silicon dioxide and graphite |
| what is another name for giant covalent structures? | macromolecules |
| give 2 properties of giant covalent structures? | very high m.p's and don't ocnduct (except graphite) |
| give to properties of metallic structures and say why | good conductors (free electrons) and bendy as the layers can slide over eachother |
| name the 4 types of structure you need to know | giant covalent, simple molecular, giant ionic and giant metallic |
| what are fullerenes? | nanoparticles that are made up of carbon |
| what is a thermosoftening polymer? | melts on heating as there are no cross links between chains, you can then remould them |
| what is a thermosetting polymer? | crosslinks, so it doesn't soften when heated, it just chars at high temperatures |
| give the conditions to make LD polyethene | 200 degrees, high pressure |
| give the conditions to make HD polyethene | low temperature and pressure with a catalyst |
| what is one mole of a substance equal to? | its relative formula mass in grams |
| give the equation for the number of moles | n=m/Mr |
| how does gas chromatography work? | a gas is used to carry substances through a coloumn packed with solid material, the substances travel at different speeds, so are seperated. retention time to the detector which is used to identify the substances |
| what does the molecular ion peak on a mass spectrometer show? | the relative molecular mass |
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