2.1 - 7-16 Flashcards
What is a radical?
A species with an unpaired electron.
What is homolytic fission?
The breaking of a covalent bond, with one of the bonded electrons going to each atom, forming two radicals.
What is heterolytic fission?
The breaking of a covalent bond with both of the bonded electrons going to one of the atoms.
What is a nucleophile?
An atom (or group of atoms) that is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.
What is an electrophile?
An atom (or group of atoms) that is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond.
What is an addition reaction?
A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.
2 reactants → 1 product
What is a substitution reaction?
A reaction in which an atom (or group of atoms) is replaced with a different atom or group of atoms.
2 reactants → 2 products
What is an elimination reaction?
Refers to the removal of a molecule from a saturated molecule to make an unsaturated molecule.
1 reactant → 2 products
What is radical substitution?
A type of substitution reaction in which a radical replaces a different atom or group of atoms.
What are the conditions of the reaction between an alkane and a halogen?
Ultraviolet light or at a temperature of about 300⁰C
What is initiation?
The first step in a radical substitution in which the free radicals are generated by ultraviolet radiation.
What is propagation?
The two repeated steps in radical substitution that build up the products in a chain reaction.
What is termination?
The step at the end of a radical substitution when two radicals combine to form a molecule.
All radicals are removed.
How is the double bond formed?
A σ - bond is formed directly between two carbon atoms by the overlap of orbitals. Each carbon contributes one electron.
A π - bond is formed above and below the plane of the carbon atoms by sideways overlap of p-orbitals. Each carbon contributes one electron.
What is a pi-bond?
The reactive part of a double bond formed above and below the plane of the bonded atoms by sideways overlap of p - orbitals.
What is the shape and bond angle of an alkene?
Trigonal planar shape.
120⁰
Which bond breaks when an alkene reacts?
The pi bond breaks.
The sigma bond remains intact.
What is electrophilic addition?
A type of addition reaction where an electrophile is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond.
What is a carbocation?
An organic ion in which a carbon atom has a positive charge.
What is a structural isomer?
Molecules with the same molecular formula but with different structural arrangements of atoms.
What are stereoisomers?
Compounds with the same structural formula, but with a different arrangement of the atoms in space.
What is E/Z isomerism?
A type of stereo isomerism in which different groups attached to each carbon of a C-C double bond may be arranged differently in space because of the restricted rotation of the double bond.
What is cis/trans isomerism?
A special type of E/Z isomerism in which there is a non-hydrogen group and hydrogen on each C of the C-C double bond.
What is fractional distillation?
The separation of the components in a liquid mixture into fractions which differ in boiling point by mean ps of distillation.
What is cracking?
Refers to the breaking down of long-chained hydrocarbons to form a mixture of shorter chained alkanes and alkenes.
What is a catalyst?
A substance that increases the rate of a chemical reaction without being used up in the process.
What is a mechanism?
A sequence of steps showing the path taken by electrons in a reaction.
What is a polymer?
A long molecular chain built up from monomer units.
What is a monomer?
A small molecule that combines with many other monomers to form a polymer.
What is addition polymerisation?
The process in which unsaturated alkene molecules (monomers) react to form a polymer.
What is an addition polymer?
A very long molecular chain, formed by repeated addition reactions of many unsaturated alkene molecules.
What is a repeat unit?
A specific arrangement of atoms that occurs in the structure over and over again.
What is biodegradable material?
A material that is broken down naturally in the environment by living organisms.
