Structual Isomers- molecules with the same molecular formula but a different structural arrangement. Different structures = different properties.
Stereoisomers- compounds with the same structural formula but different arrangement of atoms.
E (cis)/ Z (trans)- when there is a non hydrogen group and hydrogen on each C of a C=C bond.
E- transisomer = atoms on different side
Z- cisisomer = atoms on the same side
Homolytic Fission: each atom has an unpaired electon (radical)
Heterolytic Fission: one of the bonded atom takes both pair of electrons (cation+ve or anion-ve)
Nucleophile is an atom that is attracted to an electron deficient, they donate an electron pair, for example, :Br
Electrophile is an atom that attacks an area of high electron density, accepting an electron pair, for example, HBr
Organic Reagents: Reactions
Addition Reaction: 2 reactants --- 1 product
Substitution Reaction: 2 reactants --- 2 products
Elimination Reaction: 1 reactant --- 2 products
- carbon dioxide = carbon molecules
- 1/2 water= hydrogen atoms
- Caused when there is a lack of oxygen, carbon monoxide and water are formed
Carbon monoxide is colourless and odourless.
Substitution of Alkanes
- a covalent bond is BROKEN to form radicals. A Hydrogen is subsituted for a halogen atom.
1) Initiation is when the free radicals are generated by ultraviolet radiation: the radicals produced are very reactive.
2) Propogation is when the two repeated steps that build up the products.
Methane reacts with the chlorine radical and a C-H bond is broken forming methyl radical. Methyl radical reacts with chlorine, forming chloromethane.
This reaction carries on until there are no more reactants. = CHAIN REACTION.
3) Termination is the step at the end when two radicals form a molecule by combining. ALL radicals are removed to stop the reaction.
One double bond has general formula of Cn+H2n Alkenes more reactive than alkanes.
The Pi bond fixes the carbon positions, preventing rotation.
- There are 3 regions of electron density around each carbon. Pair of electrons repel each other. Trigonal Planar Shape = 120 Degrees.
Show the movement of an electron pair in the breaking/formation of a covalent bond.
- electron pair in the Pi bond is attracted to the hydrogen, bond breaks.
- New bond forms: C-H.
- H-Br bond breaks, electron pair goes to the Bromine.
- The carbocation formed is unstable and reacts with bromide ion.
Industrial use of alkenes
Industrial use of alkenes
Plastics are one of the industrial products produced from ethene.
Polymer: A long molecular chain built up from monomers.
Monomer: Small molecules that are combined to form polymers.
Addition Polymerisation is the process by which unsaturated alkene molecules (monomers) add on to a growing polymer chain, one at a time, to form a long saturated molecular chain (the addition polymer).
Radical Polymerisation: Temperature of 200 Degrees and High pressure. This leads to branching and production of polymer mixtures.
The Ziegler-Natta Process: Specialist catalyst (Titanium Chloride) and 60 Degrees. When the alkene is passed over the catalyst with a low conversion and the unreacted alkenes is passed over the catalyst repeatedly. Causes non brances poly(ethene).