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27 Cards in this Set
- Front
- Back
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What is Covalent bonding?
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The sharing of electrons
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What are simple Molecular Substances?
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The atoms form very strong covalent bonds to form small molecules of several atoms.
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The melting and boiling point for simple molecular substances are very _____ because the molecules are easily parted from each other.
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LOW
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What is broken when simple molecular substances melt or boil?
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The intermolecular forces, NOT the strong covalent bonds.
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Most Molecular substances are _____ or_____ at room temp.
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Gases and liquids
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Molecular substances dont conduct ________ ?
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ELECTRICITY because there are no Ions so there is no electrical charge.
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E.G. of weak intermolecular forces?
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-Chlorine
-Oxygen -Water |
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What are giant covalent structures called?
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Macromolecules
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Macromolecules have a _____ boiling and melting point.
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HIGH
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Macromolecules dont....
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conduct electricity (except graphite)
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E.G. of Macromolecules?
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-Diamond (very rigid so used for drill tips)
-Graphite (3 Co' bonds creates layers which slide=soft,used for pencils, conduct heat,electricity) Both made only from carbon atoms, -Silicon Dioxide (what sand is made from) |
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Metalic bonding is down to?
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'sea of free electrons'
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What is the 'proper' name for a free electron?
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Delocalised electron
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Where do 'free electerons' come from?
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The outer shell of every metal atom in the structure
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Metal conduct ____ and_______ well because of the 'free electrons' being able to move through the whole structure.
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HEAT and ELECTRICITY
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How are metals bent and shaped?
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Layers of atoms slide over each other
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What is an Alloy?
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A mix of a metal and non-metal
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Why are Alloys harder?
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Because the metal atoms will distort the layers of metal atoms therefore making it harder for them to slide over each other.
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What are very small particles called?
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Nanoparticles
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Weak intermolecular forces make?
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Thermosoftening Polymers as easy to melt and shape because individual tangled chains of atoms are free to slide over each other.
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Strong intermolecular forces make?
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Thermosetting Polymers as the chains are secured by crosslinks therefore when heated it doesnt soften.
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How is low density Polythene made?
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Heating Ethene to about 200^o under high pressure. Its flexible and used for bags and bottles.
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How is high density Polythene made?
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At a lower temperature and pressure but with a catalyst. Its more rigid and used for water tanks and drainpipes.
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What is paper Chromatography used for?
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To seperate artificial colours
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How is a machine used?
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It can analyse unknown substances
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What are the advantages of using a machine?
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-Very sensitive
-Very fast -Very accurate |
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What can Gas Chromatography be used for?
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To identify substances by seperating out a mixture of compounds.
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