Chapter 10 Structure and nomenclature of organic compounds

Question 1

Achiral

Answer 1

Not chiral

Question 2

Alkyl group

Answer 2

A group obtained by removing a hydrogen atom from an alkane, with a general formula CnH2n+1. For example, methyl is -CH3. Alkyl groups make up branches in organic compounds.

Question 3

Chin isomers

Answer 3

An isomer of an organic molecule cause by branching of the hydrocarbon chain

Question 4

Chiral

Answer 4

A chiral object is non-superimposable on its mirror image. A chiral molecule has two optical isomers called enantiomers. Chiral molecules do not have a plane of symmetry

Question 5

Chiral centre

Answer 5

A carbon atom which is attached to four different groups in a tetrahedral arrangement.

Question 6

Cis isomers

Answer 6

An isomer in which the highest priority groups attached to the carbons of a double bond are on the same side of the double bond plane

Question 7

Cis-trans isomers

Answer 7

Isomers that occur when two different groups are attached to each carbon in a carbon-carbon double bond. They occur because there is restricted rotation around the carbon-carbon double bond

Question 8

Enantiomers

Answer 8

One of a pair of molecules which are mirror images of each other but which cannot be superimposed. Enantiomers are optical isomers

Question 9

Functional group

Answer 9

An atom or group of atoms in an organic molecule which largely determines the molecule’s properties and reactions

Question 10

Geometric isomers

Answer 10

A type of stereoisomer which can arise when there is restricted rotation in a molecule such as occurs around a carbon-to-carbon double bond or in a ring structure.

Question 11

Homologous series

Answer 11

A series of organic compounds in which each member of the group differs from the previous member by -CH2. Examples are alkanes, alkenes and alcohols

Question 12

Hydrocarbon

Answer 12

A compound which contains only hydrogen and carbon atoms. Examples are alkanes and alkenes

Question 13

Isomers

Answer 13

Molecules which have the same molecular formula but which have different arrangements of atoms in 3-D space.

Question 14

Molecular formula

Answer 14

A formula which gives the type and number of atoms in a molecule.

Question 15

Optical isomers

Answer 15

A type of stereoisomer which can arise when there is restricted rotation in a molecule such as occurs around a carbon-to-carbon double bond or in a ring structure.

Question 16

Organic molecule

Answer 16

A molecule based on a hydrocarbon skeleton. Organic molecules also commonly contain other non-metal elements, such as oxygen, nitrogen, sulphur and chlorine.

Question 17

Postitional isomers

Answer 17

Isomers which arise because of different positions of the functional groups on the carbon chain

Question 18

Primary alcohol

Answer 18

An alcohol in which the carbon that is bonded to the -OH group is attached to only one alkyl group

Question 19

Saturated

Answer 19

Describes hydrocarbons or organic molecules with only single carbon-to-carbon bonds

Question 20

Secondary alcohol

Answer 20

An alcohol in which the carbon that is bonded to the -OH group is also attached to two alkyl groups. The alkyl groups may be the same or different

Question 21

Semi-structural formula

Answer 21

A formula which summarises the structure of a molecule in a single line of text

Question 22

Skeletal formula

Answer 22

A formula which represents the structural arrangement of atoms in a molecule where covalent bonds are represented as lines and where the symbols for carbon and hydrogen are omitted and where C-H bonds are not shown.

Question 23

Stereoisomers

Answer 23

Comprise optical isomers and geometric isomers. Stereoisomers are isomers where all the atoms are connected in the same order, but which still have different arrangements in 3-D space.

Question 24

Structural formula

Answer 24

A formula which represents the three-dimensional arrangement of atoms in a molecule

Question 25

Structural isomers

Answer 25

Comprise chain isomers and positional isomers, where the molecular formulae are the same but where the atoms are arranged in different ways, structurally.

Question 26

Tertiary

Answer 26

An alcohol in which the carbon that is bonded to the -OH group is also attached to three alkyl groups. The alkyl groups may be the same or different

Question 27

Tetrahedral

Answer 27

In the shape of a tetrahedron, where four points at equal distances are spread as far apart as possible in three dimensions.

Question 28

Trans isomers

Answer 28

An isomer in which the highest priority groups attached to the carbons of a double bond are on opposite sides of the double bond plane.

Question 29

Unsaturated

Answer 29

Describes hydrocarbons or organic molecules containing one or more double or triple carbon-to-carbon bonds