Topic 6 – Organic Chemistry I
In order to develop their practical skills, students should be encouraged to carry out a range of practical experiments related to this topic. Possible
experiments include cracking of artificial crude oil, extracting limonene from orange peel, dehydrating an alcohol to an alkene, preparing a simple
halogenoalkane such as 1-bromobutane, simple test tube reactions for different functional groups. Mathematical skills that could be developed in
this topic include calculating the yield of a reaction or an atom economy. Within this topic, students can consider how the polymer industry provides
useful solutions for many modern applications, but poses questions about sustainability of resources and the feasibility of recycling. They will also
encounter practical organic chemistry, showing them how chemists work safely with potentially hazardous chemicals by managing risks.
Topic 6A: Introduction to Organic Chemistry
1. know that a hydrocarbon is a compound of hydrogen and carbon only
What is the definition of a hydrocarbon?
A hydrocarbon is a compound that contains hydrogen and carbon ONLY.
2. be able to represent organic molecules using empirical formulae, molecular formulae, general formulae,
structural formulae, displayed formulae and skeletal formulae
State the difference between empirical and molecular formulae.
The molecular formula of a molecule is the total number of each element present in the molecule.
The empirical formula of a molecule is the simplest whole number ratio of each element present in the molecule.
Give the difference between displayed and condensed structural formulae.
The displayed formula of a molecule shows all the bonds in the molecule.
The condensed structural formula of a molecule shows what is attached to each carbon atom.
What is the general formula for alkenes and alkanes?
The general formula for alkenes is CnH2n.
The general formula for alkanes is CnH2n+2.
Give the definition of a skeletal formula.
A skeletal formula shows a simplified displayed formula, shown by removing hydrogen atoms from alkyl groups,
leaving just a carbon ‘skeleton’ and associated functional groups.
3. know what is meant by the terms ‘homologous series’ and ‘functional group’
What is the definition of a homologous series?
Members of a homologous series:
Have the same general formula, are members of the same functional group, have similar chemical
properties, show a trend in physical properties, and have successive members differ by -CH2-
What is the definition of a functional group?
A functional group is a set of atoms or bonds within a molecule that function together to react in similar ways – e.g.
C=C for alkenes, O-H for alcohols, and COOH for carboxylic acids.
4. be able to name compounds relevant to this specification using the rules of International Union of Pure
and Applied Chemistry (IUPAC) nomenclature. Students will be expected to know prefixes for compounds up to C10
5. classify reactions as addition, elimination, substitution, oxidation, reduction, hydrolysis or polymerisation
, 6. understand the term ‘structural isomerism’ and determine the possible structural, displayed and skeletal
formulae of an organic molecule, given its molecular formula
What is a structural isomer?
Structural isomers are molecules with the same molecular formula, but a different displayed formula (i.e. a different
configuration of atoms in the molecule). Examples are butane and methyl propane, or but-1-ene and but-2-ene.
State the three types of structural isomers.
Chain isomers – compounds with different structures of the carbon skeleton (e.g. pentane / 2-methylbutane).
Position isomers – compounds with different functional group positions (e.g. 1-bromopropane / 2-bromopropane).
Functional group isomers – compounds with differing functional groups (e.g. ethanol / methoxymethane)
7. understand the term ‘stereoisomerism’, as illustrated by E/Z isomerism (including cis-trans isomerism
where two of the substituent groups are the same)
Give the two types of stereoisomers. What are they?
Stereoisomers have the same structural formulae but a different spatial arrangement of atoms. There are two types:
Geometric (E/Z) isomers and optical isomers / enantiomers.
Topic 6B: Alkanes
8. know the general formula for alkanes
What is the general formula for alkanes?
The general formula for alkanes is CnH2n+2.
9. know that alkanes and cycloalkanes are saturated hydrocarbons
Explain why alkanes are saturated hydrocarbons.
Alkanes are classed as saturated hydrocarbons because they only contain carbon and oxygen, and only contain
carbon-carbon single bonds (NO DOUBLE BONDS).
10. understand that fuels are obtained from the fractional distillation, cracking and reforming of crude oil.
Reforming is described as the processing of straight-chain hydrocarbons into branched-chain alkanes and cyclic hydrocarbons for efficient combustion.
Describe and explain how crude oil is separated into fractions.
First, crude oil is heated to a very high temperature in a furnace, which causes the oil to boil . The hydrocarbons
(ba-dum tss)
evaporate and turn into vapours which are passed into the fractionating column. This column is hot at the bottom,
and cool(er) at the top. The hydrocarbon vapours travel up the column. As these vapours travel upwards, they
condense when they reach a part of the column that is at their boiling point. These liquid fuels are then removed.
Small-chain molecules have low boiling points and rise higher up the column before they condense. Longer chain
hydrocarbons have high boiling points and condense further down the column.
Very short-chain molecules have low boiling points, so these do not condense at all. They are removed from the top
of the fractionating column as gases.
Very long-chain hydrocarbons have very high boiling points and these remain a liquid. These are removed from the
bottom of the fractionating column as bitumen.
2
In order to develop their practical skills, students should be encouraged to carry out a range of practical experiments related to this topic. Possible
experiments include cracking of artificial crude oil, extracting limonene from orange peel, dehydrating an alcohol to an alkene, preparing a simple
halogenoalkane such as 1-bromobutane, simple test tube reactions for different functional groups. Mathematical skills that could be developed in
this topic include calculating the yield of a reaction or an atom economy. Within this topic, students can consider how the polymer industry provides
useful solutions for many modern applications, but poses questions about sustainability of resources and the feasibility of recycling. They will also
encounter practical organic chemistry, showing them how chemists work safely with potentially hazardous chemicals by managing risks.
Topic 6A: Introduction to Organic Chemistry
1. know that a hydrocarbon is a compound of hydrogen and carbon only
What is the definition of a hydrocarbon?
A hydrocarbon is a compound that contains hydrogen and carbon ONLY.
2. be able to represent organic molecules using empirical formulae, molecular formulae, general formulae,
structural formulae, displayed formulae and skeletal formulae
State the difference between empirical and molecular formulae.
The molecular formula of a molecule is the total number of each element present in the molecule.
The empirical formula of a molecule is the simplest whole number ratio of each element present in the molecule.
Give the difference between displayed and condensed structural formulae.
The displayed formula of a molecule shows all the bonds in the molecule.
The condensed structural formula of a molecule shows what is attached to each carbon atom.
What is the general formula for alkenes and alkanes?
The general formula for alkenes is CnH2n.
The general formula for alkanes is CnH2n+2.
Give the definition of a skeletal formula.
A skeletal formula shows a simplified displayed formula, shown by removing hydrogen atoms from alkyl groups,
leaving just a carbon ‘skeleton’ and associated functional groups.
3. know what is meant by the terms ‘homologous series’ and ‘functional group’
What is the definition of a homologous series?
Members of a homologous series:
Have the same general formula, are members of the same functional group, have similar chemical
properties, show a trend in physical properties, and have successive members differ by -CH2-
What is the definition of a functional group?
A functional group is a set of atoms or bonds within a molecule that function together to react in similar ways – e.g.
C=C for alkenes, O-H for alcohols, and COOH for carboxylic acids.
4. be able to name compounds relevant to this specification using the rules of International Union of Pure
and Applied Chemistry (IUPAC) nomenclature. Students will be expected to know prefixes for compounds up to C10
5. classify reactions as addition, elimination, substitution, oxidation, reduction, hydrolysis or polymerisation
, 6. understand the term ‘structural isomerism’ and determine the possible structural, displayed and skeletal
formulae of an organic molecule, given its molecular formula
What is a structural isomer?
Structural isomers are molecules with the same molecular formula, but a different displayed formula (i.e. a different
configuration of atoms in the molecule). Examples are butane and methyl propane, or but-1-ene and but-2-ene.
State the three types of structural isomers.
Chain isomers – compounds with different structures of the carbon skeleton (e.g. pentane / 2-methylbutane).
Position isomers – compounds with different functional group positions (e.g. 1-bromopropane / 2-bromopropane).
Functional group isomers – compounds with differing functional groups (e.g. ethanol / methoxymethane)
7. understand the term ‘stereoisomerism’, as illustrated by E/Z isomerism (including cis-trans isomerism
where two of the substituent groups are the same)
Give the two types of stereoisomers. What are they?
Stereoisomers have the same structural formulae but a different spatial arrangement of atoms. There are two types:
Geometric (E/Z) isomers and optical isomers / enantiomers.
Topic 6B: Alkanes
8. know the general formula for alkanes
What is the general formula for alkanes?
The general formula for alkanes is CnH2n+2.
9. know that alkanes and cycloalkanes are saturated hydrocarbons
Explain why alkanes are saturated hydrocarbons.
Alkanes are classed as saturated hydrocarbons because they only contain carbon and oxygen, and only contain
carbon-carbon single bonds (NO DOUBLE BONDS).
10. understand that fuels are obtained from the fractional distillation, cracking and reforming of crude oil.
Reforming is described as the processing of straight-chain hydrocarbons into branched-chain alkanes and cyclic hydrocarbons for efficient combustion.
Describe and explain how crude oil is separated into fractions.
First, crude oil is heated to a very high temperature in a furnace, which causes the oil to boil . The hydrocarbons
(ba-dum tss)
evaporate and turn into vapours which are passed into the fractionating column. This column is hot at the bottom,
and cool(er) at the top. The hydrocarbon vapours travel up the column. As these vapours travel upwards, they
condense when they reach a part of the column that is at their boiling point. These liquid fuels are then removed.
Small-chain molecules have low boiling points and rise higher up the column before they condense. Longer chain
hydrocarbons have high boiling points and condense further down the column.
Very short-chain molecules have low boiling points, so these do not condense at all. They are removed from the top
of the fractionating column as gases.
Very long-chain hydrocarbons have very high boiling points and these remain a liquid. These are removed from the
bottom of the fractionating column as bitumen.
2
