Module 4.1 Flashcards
What is a homologous series
Organic chemicals that have the same functional group, and only differ by ch2
What are alipathic hydrocarbonns
Hydrocarbon where the carboon atoms are joined in straight unbranched chains or straight branched chains
What are alicyclic hydrocarbons
hydrocarbons where the carbon atoms are joined together in a cyclic ring structure
What are aromatic hydrocarbons
Hydrocarbons that contain at least one benzene ring
What is a benzene ring
6 cyclic unsaturated carbon atoms
What is the formula for alkanes
CnH2n+2
What are the first 10 prefixes for alkanes / alkenes
meth
eth
prop
but
pent
hex
hept
pct
non
dec
How do you name alkyl cahins
prefix + yl
What is an alkyl chain
When you remove 1 hydrogen from an alkane
e.g methane = CH4
methyl = CH3
How do you name a substance with an alkyl group
Count the longest cahin of carbon atoms
look at which carbon the alkyl group is on, and usse the lowest number
Then write like this
x,y - (alkyl chai) - (hydrocarbon
What is the alcohol functional group
OH
What is th aldehyde functional group
COH
(The O has a double bond to the C)
What is the carboxylic acid functional group
COOH
(one of the O id duble bonded to the carbon)
What is the functional group of a haloalkane
Any halide
What is the ketone functional group
CO
(C=O)
The carbon atom must be joined to other carbon atoms
How do you naem an alcohol
Count the length of the carbon chain to find the prefix of the hydrocarbon
Take the lowest number of the carbon that the OH is on
Place the number of the carbon within the name and add ol to the end
(prefix) - x - ol
e.g Propan - 2 - ol
If the Oh is on carbon 1 the number is not needed
How do you name an alkene
Count the longest hydrocarbon name
take the smallest number of the double bond
Place the number in the name, and add ene to the end
(prefix) - x - ene
e.g But-2-ene
How do you name a haloalkane
Count the longest hydrocarbon name
take the smallest number of the carbon the halide is on
x, y - (halide) - (suffix)
e.g
2,3 - dibromo - decane
How do you name a carboxylic acid
Count the longest hydrocarbon name
A carboxyl;ic acid is always at the end
(prefix) - anoic acid
e.g Pentanoic acid
How do you name a ketone
Count the longest hydrocarbon name
take the smallest number of the C = O double bond
(prefix) - x - one
e.g propan - 2 -one
How do you name an aldehyde
Count the longest hydrocarbon name
Aldehydes area always on the first or last carbon
Prefix + al
e.g Butanal
What is the priority list
A lsit that tell you which functional group has priority
aldehide / ketone / carboxylic acid
amine
alcohol
alkene
haloalkane
methyl
How do you determine which number carbon a functional group is on
FInd the lowest number of the highest priority functional group
Keeping numbering the other functional groups in the same direction
How do you name an alcohol if there is a functional group with greater priority
It is written as a hydroxy prefix
x - hydroxy - (suffix)
e.g
3 - hydroxy - pentanoic acid
What is the displayed formula
A formula that shows ALL the bonds between the atoms, and the relative position of the atoms
e.g an OH groip in an alcohol has to be written as O-H
What is the structural formula
A formula that gives the smallest detail of atoms
Repeated units can be written in ()
alkyl chains are also written in brackets
e.g butane CH3(CH2)2CH3
What is skeletal formula
A method of drawing a hydrocarbon.
Lines are used to indicate alkyl chains, and each end of a line represents a carbon
What is molecular formula
All of the atoms in the compund written
e,g C6 H12 O6
What are structural isomers
THE same molecular formula buut different structural formulas
What are the 3 main types of structural isomers
Chain
Positional
FUnctional grop
What is a chain isomer
The same molecular formula but more branched
What is a positional isomer
The same molecular formula, but the position of the functional group changes
Alkyl chains do not move
What is a functional group isomer
The same functional group, but different functional group
E.g alkenes and cycloalkanes
What is a sterioisomer
The same structure but different arrangement in space q
What is a geometric isomer (E / Z isomerism)
An isomer caused by the restricted rotation around a molecule
Why does geometric isomerisation occur
Atoms are unable to roate around athe carbon double bond, as the pi bonds are rigid
When is e/z or cis / trans used
cis / trans is used when the substituents on each carbon atom are the same
If they are not the same e / z is used
What does the e or trans stand for in stereoisomerism
When the higher priority groups are on the opoisye side of the double bond
What does the z or cis stand for in stereoisomerism
The higher priority groups are on the same side of the double bond
How do you decide which group has higher priority in sterioisomerism
Look at the atomic numbers of the atoms bonded to the carbon.
The larger the number, the larger the priority
If the first atom is the same, look at the other atoms taht are bound to that atom
What is a reaction mechanism
Models that display the movement of electrons in a chemical reaction
What is homolytic fission
When a covalent bond is broken, an electron goes to both the bonded atoms
It is modelled using a half headed arrow
What is heterolytic fission
When a covalent bond breaks and only one atom receives both the electrons from the bonding pair
It is shown by a regular arrow
What are free radicals
Species with an unpaired pair of electrons that are trying to obtain a full octet
What is free radical substitution
The process of converting an alkane into a haloalkane using radicals
What are the 3 stages of free radical substitution called
Initiation
Propagation
Termination
What happens in initiation of free radical substitution
(2) Free radicals are created by hitting a halogen with UV light (and / or temperatures of 300°C)
(Homolytic fission)
What happens in propagation of free radical substitution
The product is formed and free radicals are regenerated
1) alkane + free radical → alkane with 1 less hydrogen (free radical) + hydrogen halide
2) Alkane free radical + halogen → product + halogen free radical
What happens in termination of free radical substitution
Free radicals react with each other to form a product
There are three possible products
What is the bond angle of hydrogens around a carbon in alkanes
There are 4 bonds creating an angle of 109.5
The shape is tetrahedral
How does boiling and melting point change with alkane chain length
As an alkane chain becomes longer its molecular mass increases.
Its surface area increases, so its surface contact with other molecules is greater (so there are more dipole - dipole forces)
More energy is required to break more forces, so the temperature required is greater
How does an alkane being branched affect its melting / boiling point
The more branched a compound is, the fewer surface area interactions there are between molecules
This means there are fewer induced dipole - dipole interactions, so the melting / boiling point is lower
How do alkane molecules attract each other
Due to electrons constantly spinning around the molecules, dipoles are induced
Induced dipole - dipole interactions (london forces) form between the molecules
What is complete combustion
Oxidising a fuel in a plentiful supply of air
What is incomplete combustion
Oxidising a fuel in a limited supply of air
Why do alkanes have low reactivity
1) The covalent bonds have high bond enthalpy (large energy needed to break them)
2) The C-H (sigma bonds) have low polarity as the electronegativity is similar between C and H
What is produced in the complete combustion of an alkane
Carbon dioxide and water are produced
What can be produced in complete combustion of alkanes
Carbon monoxide and water
Or
Carbon and water
Why do double bonds occur in alkenes
The electron clouds of the carbon atoms overlap forming a sigma bond
The π-bond is formed as electrons in adjacent p-orbitals above and bellow the sigma bond overlap
Sigma bonds always for first
Why do π bonds break first in alkenes
They have a high electron density, so are more reactive than the sigma bond
Where do π-bonds form in alkenes
Between adjacent p-orbitals, both above and below the sigma bond
Why do we call the bonding in alkenes a double bond
As it has a sigma bond and a π bond
What is the shape of an alkene around the double bond
It has three areas of electron density
-The sigma covalent bonds between carbon atoms and hydrogen
- The covalent bonds between the carbon atoms (sigma and π)
This makes a trigonal planar shape
Why are alkenes more reactive than alkanes
As they have a C=C
What are electrophiles
Electron pair acceptors
What is electrophilic addition (alkenes)
The double bond is an area of intense electronegativity and causes nearby molecules to be polarised
(The c=c repels electrons in the approaching molecules)
The c=c bond breaks and forms a bond with the partially positive part of the molecule
The carbon that does not bond becomes positive
The positive carbon attracts the negative molecule
What is hydrogenation
A reaction where hydrogen is added to an alkene to make an alkane
It requires 150°C and a catalyst such as nickel
What is halogenation
Adding a halogen (e.g Br2) to an alkene to produce a dihaloalkane
Why is hydration (of an alkene)
Reaction where an alcohol is created by adding steam to an alkene
Requires high temperature (300°C) and a phosphoric acid catalyst
What is addition polymerisation
Converting an alkene into a polymer by breaking the double bonds
Place an ‘n’ before the alkene and after the brackets in the repeating unit
What is a repeating unit
A set part of the polymer that is repeated
What is a monomer
A small molecule used to make polymers
What is a polymer
Macromolecules made from small repeating units
How are polymers disposed
Landfill
Combustion
Reusing
Recycling
Using them as organic livestock
How are landfills used to dispose of polymer waste
Large holes are dug into the landscape
These holes are lined to stop contaminants seeping into the water table
The waste is then buried
Eventually the conditions become anaerobic which slows decomposition
How is combustion used to dispose of polymer waste
- Plastics are many organic so can be burnt, releasing carbon dioxide (greenhouse gas)
- Some plastics will produce harmful gases like HCl when burnt
These can be removed by neutralising them - The chemical energy can be used to drive turbines and generate electricity
How is reusing used to dispose of polymer waste
Plastics can be reused for the same function
E.g drinks bottles
How is recycling used to dispose of polymer waste
Plastics can be separated and cleaned
Then melted down and reshaped to make new products
The quality of these products could be lower
How is polymer waste converted into organic feedstock
Chemical reactions can be used to break polymers down into small organic molecules
