Organic

Question 1

Define empirical formula.

Answer 1

A formula that shows the simplest ratio of the number of atoms of the elements present in 1 molecule of compound.

Question 2

Define molecular formula.

Answer 2

A formula that shows the actual number of atoms of the elements present in 1 molecule of the compound.

Question 3

Define structural formula.

Answer 3

A formula that shows how the constituent atoms of a molecule are joined together.

Question 4

Define homolytic fission.

Answer 4

The breaking of a covalent bond such that one electron goes to each of the atoms, forming free-radicals.

Question 5

Define a free-radical.

Answer 5

An atom or a group of atoms with an unpaired electron formed from the homolytic fission of a covalent bond and are very reactive.

Question 6

Define heterolytic fission.

Answer 6

The breaking of a covalent bond such that both the electrons go to the same atom, forming positive and negative ions.

Question 7

Define carbocation and carbanion.

Answer 7

A carbocation is a carbon species that carries a positive charge while a carbanion is a carbon species that carries a negative charge.

Question 8

Define nucleophile.

Answer 8

A negatively-charged species or a species with a lone pair of electrons seeking a positively-charged region.

Question 9

Define electrophile.

Answer 9

A positively-charged species seeking a negatively-charged region.

Question 10

Define isomerism.

Answer 10

2 or more compounds have the same molecular formula but different arrangement of the atoms in the molecules.

Question 11

Define structural isomers

Answer 11

Have the same molecular formula but different structural formula.

Question 12

Define stereoisomerism.

Answer 12

Have the same molecular and structural formulae but different arrangement of their atoms in space. Consist of cis-trans and optical isomerism

Question 13

Define optical isomerism.

Answer 13

Arises because of the ability of compounds to rotate the plane of polarisation of plane-polarized light.

Question 14

Define chiral carbon.

Answer 14

A carbon to which 4 different groups are attached.

Question 15

Define racemic mixture.

Answer 15

A mixture which contains equal quantities of each optical isomer.

Question 16

Define an enantiomer.

Answer 16

A form of an optical isomer.

Question 17

Define homologous series.

Answer 17

A family of compounds containing the same functional group and differing by a CH2 between one member and the next.

Question 18

Define substitution reaction.

Answer 18

An atom or group of atoms replaces another.

Question 19

Define addition reaction.

Answer 19

2 molecules combine to form a single product. Usually in unsaturated compounds where the double bond is broken to form a saturated compound.

Question 20

Define elimination reaction.

Answer 20

involves removal of atoms or groups of atoms from 2 adjacent atoms to form a multiple bond.

Question 21

Define hydrolysis reaction.

Answer 21

Reaction with water, catalysed by acid or base.

Question 22

Define stereochemical formula.

Answer 22

A formula that shows the spatial arrangement of bonds, atoms and groups in molecules as a 3D formula.