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C2 GCSE
Chemistry unit 2 gcse aqa
Question | Answer |
---|---|
Thermosoftening polymers | forces between chains are easy to overcome. No crosslinks. Can melt +remould these plastics. Weak intermolecular forces |
Giant covalent structures | all atoms are bonded by strong covalent bonds. v. high melting +boiling points. dont conduct electricity. *Diamond, graphite, silicon dioxide |
Thermosetting polymers | have crosslinks. holds chains together in a solid structure. the polymer doesnt soften when its heated. they're strong, hard, rigid |
Properties of metals | high melting +boiling points. Good conductors of heat & electricity (cause of free electrons) |
Low density polythene | made by heating ethene to 200*c under high pressure. flexible-used for bags n bottles |
Ionic bonds | metal+non-metal donating. atoms become ions. high melting n boiling points. dissolve easy in water- carry electric current. |
High density polythene | made at lower temp +pressure (w/catalyst) more rigid n used for water n drainpipes |
simple molecular substances | forces of attraction between molecules are v weak. low melting n boiling points. dont conduct electricity. |
Ion? | when atoms lose or gain electrons. atom becomes charged. |
convalent bonding | sharing. strongest type of bond. non-metals |
calculating moles | no. of moles= (g)/Mr |
alloy? | is a mixture of two or more elements where at least one element is a metal |
diamond's structure | 4 covalent bonds per carbon atom. the hardest natural substance. |
compounds? | chemically bonded elements |
Graphite pro | each carbon forms 3 bonds. creates layers-can slide. making it slippery soft. weak intermolecular forces between layers. |
isotopes? | different atomic forms of the same element which have the same number of protons but different numbers of neutons. |
delocalised | where electrons are free to move within structure, allows a charge to be carried |
alkene? | double bonds. unsaturated |
concentration | the amount of a substance |