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23 Cards in this Set
- Front
- Back
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what is the definition of heterolytic fission? |
when a covalent bond breaks unevenly so one atom receives both electrons. this results in a positively charged cation and a anion. XY----- X+ + X- |
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what is the definition of homolytic fission? |
when a covalent bond breaks evenly and each bonding atom receives one electron resulting in the formation of radicals. they are electrically uncharged XY------X. + Y. |
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How are haloalkanes formed |
when halogens react with alkenes in photochemical reactions (started by light). A hydrogen is replaced by a halogen such as cl or br in a radical substitution reaction. |
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what is the overall equation for the reaction of chloromethane |
CH4+CL2-------CH3CL+HCL |
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What are the 3 stages in the synthesis of chloromethane |
initiation: cl2----- 2cl. (under uv) propagation: radicals are both used and produced -CL. +CH4----- CH3. + HCL -CH3.+CL2------CH3CL+CL. Termination: two radicals join together to make a stable molecule CH3.+CL.----- CH3CL CH3.+CH3.-----C2H6 |
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What is an alkene? |
- they have the general formula cnh2n -they are hydrocarbons - double covalent bond (unsaturated |
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what are the stems when naming alkenes? |
1-meth 2-eth 3-prop 4-but 5-pent 6-hex |
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what is the bond structure of an alkene? |
it is a double bond( sigma and pi bond).The sigma bond forms forms by two orbitals overlapping in a strait line to give the highest possible electron density between the two.the pie bond is formed when two p orbitals overlap sideways( dumbell shape) |
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which is weaker, pie or sigma and why |
pie as the electron is spread above and bellow the nuclei. this means the electrostatic attraction between the nuclei and shared pair of electrons is weaker. pie bond have a low bond enthrapy |
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how reactive are alkenes and why ? |
they are quite reactive. because there are two pairs of electrons in the the bond a double bond has a high electron density. also the pie bond sticks out above and bellow the molecule so it will be attacked by particles with a low electron dencity |
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what is a stereoisomer and why can an alkene be one? |
when it has the same structural formula but a diffrent arrangent in space. Because c=c bonds mean atoms cant rotate |
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when is it an E isomer and when is it a Z isomer? |
E=when the highest priority groups are on diffrent sidesZ= when the highest priority group is on the same side |
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what are the priority rules when working out E-Z isomerism? |
-H is the lowest priority group- the one with the highest priority is the one with the highest atomic number(it must be directly bonded to a carbon) |
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when ís cis/trans used and how do we know if its cis or trans? |
when the two carbon atoms either side of the double bond have at least one group in commonCis- two identcal groups on same sideTrans-two identical groups on opposite sides |
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what is the double bond in an alkene also |
nucleophile (attracted to places that dont have enough electrons) |
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what are the stages in electrophilic attraction? |
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how do you produce an alkane from an alkene |
react it with hydrogen at 150 with a nickel catalyst |
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what is produced when a halogen and an alkene react together |
dihaloalkane. |
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what is the test for unsaturation (an alkene ) |
add bromide water and shake. it will go colourless if an alkene is present. |
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how do u make ethanol from alkenes |
hydrate by steam at 300 at a pressure of 60-70 atm with a phosphoric acid catalyst |
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what is markownikoff's rule |
if the hydrogen halide is added to a symmetrical alkene only one product is made but if it is added to an unsymmetrical one 2 products are made. |
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how is addition polymerisation written |
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do how they dispose of polymers and markofnickov rule |
jkfdn |
