4. ORGANIC CHEMISTRY
A – Introduction:
4.1 – know that a hydrocarbon is a compound of hydrogen and carbon only
o Hydrocarbon – compounds containing ONLY elements of hydrogen and carbon
4.2 – understand how to represent organic molecules using empirical formulae, molecular formulae,
general formulae, structural formulae and displayed formulae
o Empirical formula – simplest whole number ratio of atoms of each element in a compound (ethene = CH 2)
o Molecular formula – actual number of each element in a compound (ethene = C 2H4)
o Structural formula – shows the arrangement of atoms (carbon by carbon), with attached hydrogens and
functional groups (ethene = CH2CH2)
o Displayed formula – shows the symbols for each atom in a compound, with straight lines to
represent the covalent bonds
o General formula – algebraic formula that can describe any member of a family of
compounds (CnH2n) (for all alkenes)
4.3 – know what is meant by the terms homologous series, functional group and isomerism
Homologous series – series of compounds with the same general formula and similar properties
o Gradual trend in physical properties as the length of the carbon chain increases
o Difference in the molecular formula between one member and the next is CH 2
o Represented by general formula
o Similar chemical reactions
o Same functional groups
Functional group – group of atoms that determine the chemical properties and chemical reactions of a compound
o Compounds in a functional group often react in similar ways
o Determines how the compound with react
o E.g. Alkane, Alkene, Alcohol, Carboxylic acid, Esters
Isomerism – compounds with the same molecular formula and different displayed formulae
o Atoms are arranged differently
o Structural formulae are different
4.4 – understand how to name compounds relevant to this specification using the rules of International
Union of Pure and Applied Chemistry (IUPAC) nomenclature (name compounds up to 6 carbons long)
o Prefix tells you how many carbon atoms are present in the longest continuous chain in the compound
o Suffix tells you the functional group of the compound
1. Find the longest carbon chain (3 – propane)
2. Identify the group attached to the chain (methyl)
3. Numbers may go in front of the name of the compound to show the position of the branch (placed on
the second carbon twice)
4. Di is used before the compound name to show there are two methyl’s
5. Therefore 2,2 – Dimethyl propane
The group attached at the branch:
o CH3 – methyl o CH3CH2CH2 – propyl
o CH3CH2 – ethyl o CH3CH2CH2CH2 – butyl
, 4. ORGANIC CHEMISTRY
4.5 – understand how to write the possible structural and displayed formulae of an organic molecule given
its molecular formula
o Use the information given – e.g. if the molecular formula = C 2H6 o Displayed formula =
o Structural formula = CH3CH3
4.6 – understand how to classify reactions of organic compounds as substitution, addition and combustion
Substitution:
o Two or more reactants join to form 2 products
o Takes place when one functional group is replaced by another
o Needs to have UV light
o E.g. Methane + Bromine → Bromomethane + Hydrogen Bromide - CH 4 + Br2 → CH3Br + HBr
Addition:
o Two or more reactants join to from a single product
o Only works in alkenes (compounds with multiple bonds)
o E.g. Ethene + Bromine → Dibromoethane - C 2H4 + Br2 → C2H4Br2
Decolourising of the bromine water is an important test for unsaturation
Test for the presence of alkene
Alkene turns the bromine water from orange to colourless (see 4.28)
Combustion:
o Involves the reaction of a fuel with oxygen
o An organic substance reacts with oxygen to form carbon dioxide (or carbon monoxide if incomplete combustion)
and water
o Complete combustion: hydrocarbon + oxygen carbon dioxide + water
o Incomplete combusion: happens when there is not enough oxygen for complete combustion
o See more in 4.11
B – Crude oil: Antibumping granules are added
to prevent large bubbles forming
4.7 – know that crude oil is a mixture of hydrocarbons
o Crude oil – a mixture of hydrocarbons (compound only containing carbon and hydrogen)
4.8 – describe how the industrial process of fractional distillation separates crude oil into fractions
o The different compounds in crude oil are separated by Refine
fractional distillation: ry
1. The crude oil is heated until to turns into a gas
2. The vapours pass into the fractionating column (which is
cooler at the top and hotter at the bottom)
3. Vapours rise and when the substances of crude oil reach a Ker
part of the column where the temperature is lower than os
their boiling point they condense (turn back into liquid)
4. Longer hydrocarbons have higher boiling points so turn back
into liquids nearer the bottom and drain out of the column
earlier on
5. The fractions of smaller hydrocarbons, and lower BP, are
collected at the top of the fractionating column as gases
A – Introduction:
4.1 – know that a hydrocarbon is a compound of hydrogen and carbon only
o Hydrocarbon – compounds containing ONLY elements of hydrogen and carbon
4.2 – understand how to represent organic molecules using empirical formulae, molecular formulae,
general formulae, structural formulae and displayed formulae
o Empirical formula – simplest whole number ratio of atoms of each element in a compound (ethene = CH 2)
o Molecular formula – actual number of each element in a compound (ethene = C 2H4)
o Structural formula – shows the arrangement of atoms (carbon by carbon), with attached hydrogens and
functional groups (ethene = CH2CH2)
o Displayed formula – shows the symbols for each atom in a compound, with straight lines to
represent the covalent bonds
o General formula – algebraic formula that can describe any member of a family of
compounds (CnH2n) (for all alkenes)
4.3 – know what is meant by the terms homologous series, functional group and isomerism
Homologous series – series of compounds with the same general formula and similar properties
o Gradual trend in physical properties as the length of the carbon chain increases
o Difference in the molecular formula between one member and the next is CH 2
o Represented by general formula
o Similar chemical reactions
o Same functional groups
Functional group – group of atoms that determine the chemical properties and chemical reactions of a compound
o Compounds in a functional group often react in similar ways
o Determines how the compound with react
o E.g. Alkane, Alkene, Alcohol, Carboxylic acid, Esters
Isomerism – compounds with the same molecular formula and different displayed formulae
o Atoms are arranged differently
o Structural formulae are different
4.4 – understand how to name compounds relevant to this specification using the rules of International
Union of Pure and Applied Chemistry (IUPAC) nomenclature (name compounds up to 6 carbons long)
o Prefix tells you how many carbon atoms are present in the longest continuous chain in the compound
o Suffix tells you the functional group of the compound
1. Find the longest carbon chain (3 – propane)
2. Identify the group attached to the chain (methyl)
3. Numbers may go in front of the name of the compound to show the position of the branch (placed on
the second carbon twice)
4. Di is used before the compound name to show there are two methyl’s
5. Therefore 2,2 – Dimethyl propane
The group attached at the branch:
o CH3 – methyl o CH3CH2CH2 – propyl
o CH3CH2 – ethyl o CH3CH2CH2CH2 – butyl
, 4. ORGANIC CHEMISTRY
4.5 – understand how to write the possible structural and displayed formulae of an organic molecule given
its molecular formula
o Use the information given – e.g. if the molecular formula = C 2H6 o Displayed formula =
o Structural formula = CH3CH3
4.6 – understand how to classify reactions of organic compounds as substitution, addition and combustion
Substitution:
o Two or more reactants join to form 2 products
o Takes place when one functional group is replaced by another
o Needs to have UV light
o E.g. Methane + Bromine → Bromomethane + Hydrogen Bromide - CH 4 + Br2 → CH3Br + HBr
Addition:
o Two or more reactants join to from a single product
o Only works in alkenes (compounds with multiple bonds)
o E.g. Ethene + Bromine → Dibromoethane - C 2H4 + Br2 → C2H4Br2
Decolourising of the bromine water is an important test for unsaturation
Test for the presence of alkene
Alkene turns the bromine water from orange to colourless (see 4.28)
Combustion:
o Involves the reaction of a fuel with oxygen
o An organic substance reacts with oxygen to form carbon dioxide (or carbon monoxide if incomplete combustion)
and water
o Complete combustion: hydrocarbon + oxygen carbon dioxide + water
o Incomplete combusion: happens when there is not enough oxygen for complete combustion
o See more in 4.11
B – Crude oil: Antibumping granules are added
to prevent large bubbles forming
4.7 – know that crude oil is a mixture of hydrocarbons
o Crude oil – a mixture of hydrocarbons (compound only containing carbon and hydrogen)
4.8 – describe how the industrial process of fractional distillation separates crude oil into fractions
o The different compounds in crude oil are separated by Refine
fractional distillation: ry
1. The crude oil is heated until to turns into a gas
2. The vapours pass into the fractionating column (which is
cooler at the top and hotter at the bottom)
3. Vapours rise and when the substances of crude oil reach a Ker
part of the column where the temperature is lower than os
their boiling point they condense (turn back into liquid)
4. Longer hydrocarbons have higher boiling points so turn back
into liquids nearer the bottom and drain out of the column
earlier on
5. The fractions of smaller hydrocarbons, and lower BP, are
collected at the top of the fractionating column as gases
