module 4: core organic chemistry Flashcards
what are structural isomers?
compounds with the same molecular formula but different structural formulae
what is a hydrocarbon?
a compound that contains only hydrogen and carbon
what does saturated mean?
containing single bonds only
what does unsaturated mean?
containing a double carbon-carbon bond
what is a skeletal formula?
a simplified organic formula
what is a homologous series?
a series of organic compounds with the same functional group (similar chemical properties) whose successive members differ by the addition of a -CH2- group
what is the general formula for alkanes?
CnH2n+2
what are alkanes?
saturated hydrocarbons
what are alkenes?
unsaturated hydrocarbons
what is a functional group?
the part of the organic molecule responsible for its chemical reactions
what are the products of the complete combustion of alkanes?
carbon dioxide + water
what are the products of the incomplete combustion of alkanes?
carbon monoxide (or carbon) + water
describe the reactions of alkanes with halogens
- alkanes react with halogens, but only in the presence of sunlight
- high energy UV radiation present in sunlight provides the initial energy for a reaction to take place
what type of reaction is that of alkanes with halogens?
a substitution reaction - a hydrogen atom in the alkane is substituted by a halogen atom
what are the three stages that make up the mechanism of the bromination of alkanes?
step 1 = initiation
step 2 = propagation
step 3 = termination
describe what happens in the first stage of the bromination of alkanes
stage 1 = initiation
- the reaction is started when the covalent bond in a bromine molecule is broken down by homolytic fission
- each bromine atom takes one electron from the pair, forming two highly reactive bromine radicals
- energy for this bond fission is provided by UV radiation
Br - Br –> Br* + Br*
what is a radical?
a very reactive species with an unpaired electron
describe what happens in the second stage of the bromination of alkanes
stage 2 = propagation
- the reaction propagates through two propagation steps, a chain reaction
Propagation step 1: CH₄ + Br* –> ·CH3 + HBr
Propagation step 2: ·CH3 + Br2 –> CH3Br + Br*