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What does nomenclature mean?
The system used for naming organic compounds
Molecular formula
The actual formula
Empirical formula
Simplest whole number ratio of atoms in a molecule
Displayed formula
Shows every atom and every bond
Structural formula
Shows the arrangement of atoms without showing bonds
Homologous series
A series of organic compounds with the same functional group
Functional group
A group of atoms responsible for characteristics
General formula of Alkanes
CnH2n+2
General formula of alkenes
CnH2n
Saturated
Only single bonds
Unsaturated
At least one double carbon bond
Structural isomerism
Same molecular formula but different structural formula
What are the 3 ways in which structural isomers can be formed?
Alkyl group can be in different places
functional group position
different functional group
Stereoisomers
organic compounds with the same molecular formula but have different arrangements
What is E/Z isomerism and how are the decided?
caused by the limited rotation around a C=C bond
If the two substitutes with the highest Mr are on the same side then Z, if not the E
Cis-trans isomerism
A special type of E/Z isomerism where the two substituents on each carbon atom are the same
What is homolytic fission?
It happens when each bonding atom receives one electron from the bonded pair forming two radicals
What is heterolytic fission?
When one bonding atom receives both electrons from the bonding pair
What are radicals?
Highly reactive neutral species
How is a covalent bond formed from two radicals?
The radicals collide and the electrons are involved in the bond formation
What is an alkane?
A saturated hydrocarbon containing C-H bonds only
How are alkane fuels obtained
From the fractional distillation, cracking and reforming of crude oil
Describe the process of fractional distillation
Oil is preheated and passed through column
fractions condense at different heights
larger molecule= larger London forces
similar molecules condense at same height
small molecules condense at lower temperatures
What is cracking?
The process of converting large hydrocarbons to smaller molecules by breakage of C-C bonds
What is the reforming of crude oil
the process of straight chain hydrocarbons into branched-chain alkanes and cyclic hydrocarbons for efficient combustion
What is the shape and angle of an alkane?
Tetrahedral 109.5
Describe the sigma bond in an alkane
a covalent bond which has a direct overlap of the electron clouds of the bonding atoms
How reactive are alkanes
Very unreactive
What reactions will alkanes undergo?
combustion and reaction with halogens?
What type of reaction is combustion?
oxidation
What is complete combustion?
combustion that occurs with plentiful supply of air
What are the products of complete combustion when alkanes are used?
carbon dioxide and water
What is incomplete combustion and what products are formed in the case of alknes?
Combustion in a limited supply of oxygen
water, CO2, CO
What pollutants are formed in the combustion of alkanes?
Carbon monoxide, oxides of nitrogen and sulfur, carbon particulates and unburned hydrocarbons
What is the environmental impact of soot?
Asthma, cancer and global warming
What are the environmental impacts of nitrogen oxides?
NO is toxic and can form smog
NO2 is toxic and acidic and forms acid rain
What are biofuels?
fuels developed from renewable resources. Alcohols and biodiesel are examples
How are halogenoalkanes formed from alkanes?
Radical substitution
In the presence of what does alkanes react with halogens
UV light
What are the three stages of free radical substitution?
Initiation, propagation and termination
What is initiation in free radical substitution?
breaking halogen bond to form free radicals
What is propagation in free radical substitution?
chain part of the reaction where products are formed but free radicals remain
What is termination in free radical substitution?
free radicals removed, stable products formed
Write the initiation equation for the reaction of CH4 with Cl to form CH3Cl
Cl2—> 2Cl*
Write the propagation equations for the reaction of CH4 with Cl to form CH3Cl
Cl*+CH4—> HCl + CH3*
*CH3 + Cl2 —> CH3Cl + Cl*
Write the termination equations for the reaction of CH4 with Cl to form CH3Cl
*CH3 + Cl* —> CH3Cl
2Cl* —> Cl2
CH3 + CH3 —> CH3CH3
What are the limitation of free radical substitution?
If there is excess halogen further substitution will take place therefore the desired product will be harder to separate from the others
What are alkenes?
Unsaturated hydrocarbons that contain at least one C=C bond made up of a pie bond and a sigma bond
How is a pie bond formed
Electrons in the adjacent p orbitals overlap above are below the carbon atoms
What bond restricts the rotation of carbon bonds?
pie bond
What is the angle and shape of a double bond?
Trigonal planar 120
What is the qualitative test for alkanes?
This test for C=C bond using bromine water. If the alkane is present, bromine water decolourises
Are alkenes or alkanes more reactive? And why?
More reactive due to high electron density of double bond and the fact the pi-bond is slightly easier to break
What intermolecular forces of attraction do alkenes have?
Only London forces due to non-polar bonds
What are the types of isomers that can be formed using alkenes?
E/Z isomers- due to the restricted rotation
Cis-trans isomers- if two of the same substituents are attached to each other
What is an electrophile?
species that are electron pair acceptors
What conditions are needed for the electrophilic addition of H20 to an alkene?
steam in the presence of an acid catalyst usually phosphoric acid
What are the products of the hydration reaction?
An alcohol
What conditions are needed for the electrophilic addition of a hydrogen halide to an alkene?
Hydrogen halide gases must be at room temperature
How does a molecule with a non-polar bond react as if it is an electrophile?
C=C bond with a high electron density induces a temporary dipole in the halogen molecule
What is the reaction called when a halogen is added to an alkene>
halogenation
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