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50 Cards in this Set
- Front
- Back
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what is the structure of an ionic compound |
giant ionic lattices regular arrangment |
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what does ionic compounds have |
strong electrostatic forces of attraction between oppositely charged ions in all directions |
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what are the properties of ionic compounds |
high melting / boiling points ions free to move can carry electric current dissolve easily in water |
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what are the 7 covalent bonding examples |
hydrogen H2 chlorine Cl2 methane CH4 hydrogen chlorine HCl ammonia NH3 water h2O oxygen O2 |
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what are the 2 types of covalent substances |
simple molecular substances giant covalent structures |
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properties of simple molecular substances |
strong covalent bonds between atoms made up of small molecules of several atoms weak intermolecular forces low boiling and melting points gases/ liquids at room temperature but can be solids dont conduct electricity - no ions no electrical charge |
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what are giant covalent structures called |
macromolecules |
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properties of macromolecules |
all atoms bonded to each other by strong covalent bonds high melting and boiling points dont conduct electricity not even when molten no charged ions |
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what are the main examples of macromolecules |
diamond silicon dioxide (silica) graphite |
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properties of diamond |
each C atom has 4 covalent bonds rigid giant covalent structure hardest natural substance used in drill tips |
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properties of silica |
what sand is made out of one grain of sand is one giant structure of silicon and oxygen |
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properties of graphite |
each C atom has 3 covalent bonds layers slide over each other soft and slippery can be rubbed off onto paper due to loose layers weak intermolecular forces between layers non metal conducts heat/ electricity each C atom has delocalised electrons to conduct electricity |
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what are nano particles |
really tiny particles 1-100 nanometers across 1nm = 0. 000 000 001m |
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what do nano particles contain |
a few 100 atoms |
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what do nanoparticles include |
fullerenes |
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what are fullerenes |
molecules of C shaped like hollow balls or closed tubes C atoms arranged in hexagonal rings different fullerenes |
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give an example of a shape memory alloy |
nitinol |
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what is nitinol and its characteristics |
metal alloy bend twist like rubber bend too far stays bent above certain temperature goes back to remembered shape |
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what is nitinol used for |
glasses frames dental braces - mouth warms tries to pull teeth back with it |
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how are nanotubes formed |
fullerenes joined together |
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what are nanotubes |
tiny hollow carbon tubes few nano metres across |
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what are the properties of nano tubes |
covalent bonds = strong used to reinforce graphite in tennis rackets |
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what can nanoparticles be used to make 7 things |
catalysts sensors stronger lighter building materials cosmetics such as sun tan cream deliver drugs - nano medicine lubricant coatings electric circuits in computer chips |
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why are nanoparticles good for catalysts |
large surface area to volume ratio |
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why are nanoparticles being used to make cosmetics |
don't leave white marks on skin |
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why are nanoparticles being used in nano medicine |
fullerenes absorbed more easily than other particles so deliver drugs to cells which need it |
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why are nanoparticles used for lubricant coatings |
reduce friction like ball bearings used in artificial joints gears |
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what are the characteristics for polymers with weak forces |
individual tangled chains of polymers weak intermolecular forces slide over each other |
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strong forces |
stronger intermolecular forces between the polymer chains called crosslinks - hold chains together |
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properties of thermosoftening polymers |
no cross links weak forces between chains easy to melt cools and changes shape remould able
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properties of thermosetting polymers |
have crosslinks chains in solid structure don't soften when heated tough , strong , hard , rigid |
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what affects a polymers properties |
starting materials and reaction conditions |
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how is low density polythene made what is it used for |
heating ethene to about 200 C - at high pressure flexible used for bags bottles |
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how is high density polythene made what is it used for |
lower temp pressure with catalyst more rigid - water tanks drain pipes look in book for table revision |
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what separates artificial colours |
paper chromatography |
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what is the 1st step in paper chromatography |
extract the colour from a food sample place it in small cup with few drops of solvent solvent can be water ethanol salt water |
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what is the 2nd step in paper chromatography |
put spots of coloured solution on pencil baseline on filter paper no pen as it dissolve messing it up |
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what is the 3rd step in paper chromatography |
roll up sheet put in beaker with solvent baseline must be above level of solvent |
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what is the 4th step in paper chromatography |
solvent seeps up paper taking dyes with it different spots from dyes in different places |
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what do you have to be careful for in paper chromatography |
chromatogram with 4 spots = at least 4 spots but not exactly 4 dyes as 5 dyes with 2 making a spot in same place can't happen with 3 dyes as 1 dye can't split into 2 spots |
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what are the advantages of using machines |
very sensitive very fast - can be automated very accurate |
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what can gas chromatography be used for |
to identify substances separates out a mixture of compounds to help identify substances present |
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what is the gas for |
used to carry substances through a column packed with a solid material |
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how are the substances separated |
travel through the container at different speeds so they are separated |
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what is the retention time how can it be used |
the time it takes to reach the detector used to identify the substance |
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what does the recorder do |
draws a gas chromatograph |
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what does the number of peaks show |
the number of different compounds in the sample |
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what shows the retention time of each substance |
the position of the peaks |
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what is GC-MS |
when the gas chromatography column is linked to the mass spectrometer identifies the substance leaving the column very accurately |
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what can you work out from the graph it draws |
the relative molecular mass of each of the substances by reading off the molecular ion peak |
