Alkanes Flashcards
What types of bonds does carbon form in compounds?
Covalent
How many bonds does carbon always form?
4 covalent bonds
Molecular formula
The number of atoms of each type of element in a molecule
Empirical formula
The simplest ratio of atoms of each type of element in a compound
Structural formula
This shows the arrangement of atoms in the molecule
Displayed formula
This shows all the bonds between the atoms in a molecule
Skeletal formula
This shows the shape of the carbon skeleton
Structural isomers
Compounds which have the same molecular formula but different structural formula
Functional group
A group of atoms responsible for the characteristic reactions of a compound
Alcohol functional group
OH
Carboxylic acid functional group
COOH
Amine functional group
NH2
Alkene functional group
C=C
Chloro functional group
Cl
Aldehyde functional group
CHO
Homologous series
A family of compounds containing the same functional group and the same general formula but with each successive member has an extra CH2
Hydrocarbons
Compounds containing carbon and hydrogen only
Saturated hydrocarbon
Only contains C-C single bonds
Unsaturated hydrocarbon
Contains a C-C multiple bond
Aliphatic hydrocarbon
Branched, unbranched or non aromatic ring
Alicyclic hydrocarbon
Non aromatic ring
Aromatic hydrocarbon
Contains one or more benzene rings
The general formula of an aliphatic alkane
CnH2n+1
What is the structure of an aliphatic alkane?
They can have branched or unbranched chains
What type of hydrocarbon are alkanes?
Saturated
What types of bonds are the C-C and C-H bonds in alkanes?
Sigma bonds
Sigma bonds
The overlap of orbitals between bonding atoms
What is the bond angle and bond shape in alkanes?
109.5 and tetrahedral
Why do alkanes not react with most common reagents?
Because they have high bond enthalpies due to strong bonds and they have a low polarity of the sigma bonds due to carbon and hydrogen having similar electronegativities
Which alkanes will show structural isomerism?
Those with 4 or more carbons
The general formula of a cyclic alkane?
CnH2n
What two factors does the boiling points of alkanes depend on?
Chain length and chain branching
What is the trend in boiling points with chain length in alkanes?
As the number of carbons increase, the boiling points will increase
Explain the trend in boiling points with chain length in alkanes?
As the number of carbons increase there is more points of contact so there are more London forces present so more energy is needed to overcome the forces
What is the trend in boiling points with chain branching in alkanes?
Branched chain alkanes have lower boiling points than their unbranched isomers
Explain the trend in boiling points with chain branching in alkanes?
As the branching increases there is less points of contact so there is less London forces present so less energy is needed to overcome the forces
Complete combustion
In a plentiful supply of oxygen, carbon dioxide and water are produced
Incomplete combustion
When insufficient oxygen is present, carbon monoxide and water are produced and can also result in the formation of carbon and water
Halogenation
When alkanes react with halogens such as chlorine and bromine
What are the conditions of halogenation?
UV light
What is the type of mechanism in halogenation?
Radical substitution
What is the type of bond breaking in halogenation?
Homolytic fission
Homolytic fission
The breaking of a covalent bond to form 2 radicals
What are the products of halogenation?
Haloalkane + either HCl or HBr
Initiation step of halogenation
Chlorine radicals are produced because UV light has sufficient energy to break the Cl-Cl bond
Radicals
Species that contain unpaired electrons
Propagation step of halogenation
A radical reacts with a molecule, and a new radical and molecule are produced, leading to a chain reaction
Termination step of halogenation
Two radicals combine and the reaction sequence stops
What are two limitations of halogenation reactions?
Further substitution and substitution on different carbons
