when electrons are shared between two or more non-metals
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explain giant covalent srtuctures
very strong/ strong intermolecular bonds.
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explain graphites properties
only 3 carbon bonds/ free electon conducts electricity/ lose layers which rub off on paper.
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metalic structures have...
free electrons/ carry electricity/ have strong forces of electrostatic attraction
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what are alloys and why are they used?
mixture of metals, with disorted layer to make harder
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name a smart material
nitinol 'shape memory' can bend when cool, but if placed in heat return to remembered shape. used in braces and glasses frames
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nano particles (fullerens) are what?
carbon atoms bonded together in hexagons or tubes, covalent bonds. very strong
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uses of nano-particles
sun cream.. get in small pores/ for small light building materials/ deliver drugs to specific cells as can be absorbed easier.
12 of 22
name two types of polymers
thermosoftening- weak bonds, tangled chains which can easily be melted and remoulded. Thermosetting- strong intermolectuar bonds, crosslinks, high melting point so strong and hard
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what is percentage yield
the percentage of product produces compared to the predicted
14 of 22
name a chromotography method..
gas- carries substances through a column at different speeds, reaching the mass spectrometer at different times. Paper- for seperating dyes, from a baseline different dyes rise to different places on the paper
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name 4 factors which effect rates of reaction
temperature- concentration- catalyst- surface area of solids
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how do you measure the rate of reaction?
through precipitation- how quick the solution takes to disappear change in mass- time takes to drop volume of gas given off- more gas = faster
17 of 22
name 4 features which increase the 'collision theory'
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