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Worksheet 10.1
Chapter 10: Organic chemistry – glossary
Addition reaction A reaction in which two reactants combine to form a single product. This type of
reaction is typical of unsaturated compounds.
Alcohol A homologous series containing the functional group –OH. Their general formula is
CnH2n + 1 OH.
Aldehyde A homologous series containing a carbonyl group –CHO. Aldehydes are formed by the
gentle oxidation of primary alcohols or by the reduction of carboxylic acids.
Alkane Saturated hydrocarbons. They have the general formula CnH2n + 2.
Alkene Unsaturated hydrocarbons. They contain a carbon–carbon double bond. They have the
general formula CnH2n.
Amine A homologous series containing the functional group –NH2. Secondary and tertiary amines
respectively have one or two of the hydrogen atoms substituted by alkyl groups.
Carbocation A species formed as an intermediate during a reaction that has a positive charge on a
carbon atom. Tertiary carbocations are more stable than secondary which are more stable than primary,
due to the positive inductive effect of the alkyl groups.
Carboxylic acid
A homologous series containing the organic acid group –COOH.
Catenation The formation of chains of atoms in compounds. Carbon has the ability to do this to a
large extent, which is one of the reasons for the vast numbers of organic compounds that exist.
Condensed structural formula A representation of the structural formula that contains the minimum
information for the sequence of atoms in the molecule to be known non-ambiguously.
Curly arrow A convention for depicting the movement of an electron pair in a reaction mechanism.
The arrow is drawn from the site of the electron availability to the site of electron deficiency.
Empirical formula
The simplest whole number ratio of the atoms in a compound.
Ester Compounds which contain the group –COOR. They are the product of the reaction between
carboxylic acids and alcohols.
Fossil fuels Fuels that are derived from the remains of living organisms. They include coal, oil, gas,
peat, etc. When burned they produce carbon dioxide and water in exothermic reactions.
Fractional distillation The process used to separate a mixture of liquids according to their boiling
points. It is used for the separation of crude oil into fractions, which have a smaller range of boiling
points.
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Free radical A species that contains an unpaired electron and is highly reactive. Radicals form from
homolytic fission.
Functional groups
compound.
An atom or small group of atoms that gives characteristic properties to the
Greenhouse gases Gases which absorb longer wave-length (infrared) radiation and so prevent the reradiation of this from the earth, causing an increase in the temperature – global warming. The most
common greenhouse gases are carbon dioxide, methane and water vapour.
Halogenoalkane
Homologous series containing a halogen atom as the functional group.
Heterolytic fission When a covalent bond breaks in a reaction and both the bonded electrons go to
one of the products, so giving rise to two oppositely charged ions.
Homologous series Families of organic compounds whose members can be represented by the same
general formula, with successive members differing by –CH2. Members of the same homologous series
show similar chemical properties and show a gradation in physical properties.
Homolytic fission When a covalent bond breaks in a reaction and each of the bonded electrons goes
to one of the products, so giving rise to two free radicals.
Hydration
alcohols.
The addition of water to a compound. For example, alkenes are hydrated to form
Hydrocarbon
Hydrogenation
form alkanes.
A compound containing carbon and hydrogen only.
The addition of hydrogen to a compound. For example, alkenes are hydrogenated to
Isomers Molecules which have the same molecular formula, but different structural formulas or
different arrangements of the atoms in space.
IUPAC International Union of Pure and Applied Chemistry. It is best known for its system of
nomenclature for organic compounds.
Ketone A homologous series containing a non-terminal carbonyl group R–CO–R. Ketones are
formed by the oxidation of secondary alcohols.
Leaving group
reaction.
An atom or group of atoms that is displaced during a substitution or an elimination
Molecular formula
empirical formula.
The actual number of atoms present in a molecule. It is a multiple of the
Monomer A molecule used as the building block of a polymer. Monomers may react together by
addition reactions giving rise to addition polymers; or by condensation reactions, giving rise to
condensation polymers.
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Nomenclature A precise means of naming entities so that they can be communicated nonambiguously. Organic chemistry uses the system of IUPAC nomenclature.
Nucleophile An electron-rich species that is therefore attracted to parts of molecules that are electron
deficient. Nucleophiles have a lone pair of electrons and may also have a negative charge.
Nucleophilic substitution A substitution reaction in which a nucleophile is the attacking species on a
molecule, and substitutes for an atom or group in the molecule.
Polymer A long chain molecule made of repeating sub-units known as monomers.
Polythene An addition polymer of ethane with the formula for the repeating unit being –(CH2)n.
Positive inductive effect The tendency of an atom or group to push electrons away from itself. These
groups, such as alkyl groups, are also known as electron-releasing groups.
Primary carbon atom
hydrogen atoms.
A carbon atom that is attached to the functional group and also to at least two
PVC Polyvinylchloride, the addition polymer of chloroethene. The formula for its repeating unit is
–CH2CHCl–.
Reaction pathways A series of linked reactions in which a reactant is converted in several steps into
a product. The product of the first step is the reactant for the second step, etc.
Reflux condenser Apparatus used to prolong a reaction when the products may be volatile and
escape before they have time to react completely. It consists of a vertical distillation column, which
allows escaping vapour to be condensed and returned to the reaction vessel.
Repeating unit
chain.
The smallest part of a polymer which shows how the units are linked to form the
Saturated A compound which contains only single bonds between carbon atoms, no carbon–carbon
double or triple bonds.
Secondary carbon atom A carbon atom that is attached to the functional group and also to one
hydrogen atom.
SN1 Substitution nucleophilic unimolecular. A substitution reaction in which a nucleophile attacks a
molecule and the mechanism involves a single reactant in the rate-determining step. It is characteristic
of the reactions between halogens and tertiary halogenoalkanes.
SN2 Substitution nucleophilic bimolecular. A substitution reaction in which a nucleophile attacks a
molecule and the mechanism involves two reactants in the rate-determining step. It is characteristic of
the reactions between halogens and primary halogenoalkanes.
Stereochemical formula A representation of a structural formula which shows the relative positions
of atoms and groups around carbon in three dimensions.
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Steric hindrance The effect where a chemical reaction is slowed or prevented by the presence of one
or more bulky groups on a molecule, which prevent the approach of another reactant to the reaction
site.
Structural formula
A representation of a molecule, showing the order of attachment of its atoms.
Structural isomers Compounds which have the same molecular formula but different structural
formulas – different order of attachment of the atoms.
Substitution reaction A reaction where one atom or group of atoms in a compound is replaced by a
different atom or group. This type of reaction is typical of saturated compounds.
Tertiary carbon atom A carbon atom that is attached to the functional group and also to three alkyl
groups. It is not bonded to any hydrogen atoms.
Unsaturated
A compound that contains a double or triple bond between carbon atoms.
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