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41 Cards in this Set
- Front
- Back
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Homologous series definition |
A family of organic compounds with the same function group, in which each successive member increases by a CH₂ unit |
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Alkyl functional group |
CₓH₂ₓ₊₁ |
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What is the functional group responsible for? |
A compound’s reactivity |
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Methyl |
CH₃ |
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Ethyl |
C₂H₅ |
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Saturated definition |
Doesn’t contain a C=C |
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Unsaturated definition |
Contains a C=C |
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Aliphatic definition |
Hydrocarbon where the carbons are joined in straight unbranched or branched chains |
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Alicyclic definition |
Hydrocarbons where the carbon atoms are joined together in a non-aromatic ring structure |
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aromatic definition |
Hydrocarbons with a benzene (C₆H₆) ring structure |
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general formula of alkenes |
CnH2n |
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functional group of alkenes |
C=C |
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are alkenes saturated or unsaturated |
unsaturated |
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what does the C=C do to the atoms the carbons are bonded with? |
holds the atoms in a fixed position - no rotation around the double bond |
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sigma (σ) bond |
covalent bonds formed by the head-on overlapping of two orbitals - increased electron density between the nuclei - the strongest type of covalent bond |
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pi (π) bond |
a covalent bond formed by the sideways overlapping of two p orbitals - increased electron density above and below the plane of carbon atoms |
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how does the C=C form in alkenes? |
- each carbon forms 3 σ bonds (with two hydrogens and another carbon) - the last electron in the outer shell of each carbon is in a p orbital - these p orbitals form a π bond as the second bond in the C=C |
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why are alkenes more reactive than alkanes? |
the pi bond in the C=C is weaker than the sigma bonds so it beaks easier to react |
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heterolytic fission |
when a bond breaks and one atom takes both electrons - forms a negative ion and a positive ion |
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homolytic fission |
when a bond breaks and each atom takes one of the electrons in the pair - forms two radicals |
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radical definition |
a species with an unpaired electron |
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electrophile definition |
an atom/group of atoms which is attracted to an electron dense centre/atom where it accepts a pair of electrons to form a covalent bond |
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electrophilic addition definition |
an addition reaction where the first step is attack by an electrophile on a region of high electron density |
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which molecules undergo electrophilic addition reactions |
alkenes |
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electrophilic addition reactions of alkenes |
- hydrogenation - hydration - alkene + hydrogen halide - halogenation |
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hydrogenation of alkenes |
alkene + H₂ → alkane - needs a nickel catalyst and 423K |
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kelvin to celcius |
OK = -273°C |
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halogenation of alkenes |
alkene + halogen → haloalkane - needs RTP |
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addition definition |
when molecules are added to an unsaturated molecule to make one saturated product |
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hydration of alkenes |
alkene + water (g) → alcohol - needs phosphoric acid catalyst and steam |
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addition polymerisation of alkenes |
- pi bond breaks so the electrons can bond with a neighbouring carbon atom - draw alkene with the C=C in the centre and alkyl groups around monomer → poly(monomer) |
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how many carbon atoms are in a repeat unit of a polymer |
2 in the middle (not part of alkyl groups) |
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carbocation stability |
the carbon with the most alkyl groups around it is the most stable and will form a carbocation - forms the major product e.g. propene + bromine - can have 1-bromopropane or 2-bromopropane - the 2nd carbon has 2 methyl groups but the 1st only has 1 ethyl - secondary carbocation is more stable so 2-bromopropane is the major product |
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incineration of polymers |
Polymers that cannot be recycled (made from petroleum or natural gas - high energy level) are incinerated and used to produce heat and electricity |
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pros of recycling polymers |
conserves finite resources and reduces the amount in landfill |
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what are alkene polymers derived from? |
usually crude oil which is finite |
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why are alkene-based polymers used |
unreactive so it's suitable for storing food and medicines |
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cons of alkene-based polymers |
non-biodegradable kill marine life |
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feedstock |
breaking down polymers into starting materials to form new polymers - can use unsorted or unwashed ones unlike with recycling |
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bioplastics and biodegradable polymers |
polymers made from plant starch, cellulose, oils - renewable - sustainable - break down so environment isn't damaged |
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photodegradable polymers |
adding UV light to polymers breaks bonds and starts the degradation process |
