Alkanes
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Define aliphatic
A compound containing carbon and hydrogen joined together in straight chains, branched chains, and non-aromatic rings
Define homologous series
A family of organic compounds having the same functional group but with each successive member differing by CH2
Define functional group
A group of atoms responsible for the characteristic reactions of a compound
Define alicyclic
An aliphatic compound arranged in non-aromatic rings (with or without side chains)
Define aromatic
A compound containing a benzene ring
Define saturated
A compound containing only C-C single bonds
Define unsaturated
A compound containing at least one mutiple C-C bond
What is the general formula of an alkane?
C2H2n+2
Define structural isomer
Compounds with the same molecular formula but different structural formula
What are the 3 ways structural isomerism can occur?
• chain isomers • position isomers • functional group isomers
Define hydrocarbon
A compound containing only carbon and hydrogen atoms
Are alkanes saturated or unsaturated hydrocarbons?
Saturated
What shape forms around the carbon atoms in an alkane?
Tetrahedral
What 2 factors affect the boiling points of alkanes?
• chain length • extent of branching
As branch length increases, what happens to the boiling point?
Boiling point increases
Why does boiling point increase with chain length?
• larger chain length means greater contact area betwen molecules • meaning London forces between molecules will be greater • so more energy is required to overcome the forces
What happens to the boiling point as branching increases?
Boiling point decreases
Why does boiling point decrease as branching increases?
• the more branched a molecule, the lower the contact area • weaker London forces between molecules • less energy is needed to overcome the intermolecular forces
Why are alkanes relatively unreactive?
C-C bonds are non-polar C-C and C-H bonds are strong C-H bonds are non-polar as the elements have similar Pauling values
What two reactions do alkanes undergo?
• combustion with oxygen • reaction with halogens to form haloalkanes
How can you tell complete combustion is occurring?
A blue flame is seen
How can you tell incomplete combustion is occurring?
A yellow flame is seen and/or the formation of soot
Give the equation for the complete combustion of methane
CH4 + 2O2 → 2H2O + CO2
When does incomplete combustion occur?
When there is insufficient oxygen