17/18 - organic 2 & 3

Question 1

chiral

Answer 1

refers to an atom in a molecule that allows it to exist as non-superimposable forms. it can also refer to the molecule itself

Question 2

asymmetric

Answer 2

refers to a carbon atom in a molecule that is joined to four different atoms or groups

Question 3

enantiomers

Answer 3

isomers that are related as objects and mirror image

Question 4

optical activity

Answer 4

a substance shows optical activity if it rotates the plane of polarisation of plane-polarised light

Question 5

plane-polarised light

Answer 5

monochromatic light that has oscillations in only one plane

Question 6

unpolarised light

Answer 6

has oscillations in all planes at right angles to the direction of travel

Question 7

polarimeter

Answer 7

the apparatus used to measure the angle of rotation caused by a substance

Question 8

polariser

Answer 8

a material that converts unpolarised light into plane-polarised light

Question 9

analyser

Answer 9

a material that allows plane-polarised light to pass through it

Question 10

racemic mixture

Answer 10

an equimolar mixture of two enantiomers that has no optical activity

Question 11

bimolecular mechanism

Answer 11

has two species reacting in the rate-determining step

Question 12

unimolecular mechanism

Answer 12

has one species reacting in the rate-determining step

Question 13

nucleophilic addition

Answer 13

mechanism in which a molecule containing two atoms or groups is added across a polar double bond (usually C=O), and the attacking species in the first step is a nucleophile

Question 14

derivatives

Answer 14

compounds formed from other compounds, especially when the properties of the derivatives can be used to identify the original compound

Question 15

hydrolysis

Answer 15

the breaking of a compound by water into two compounds

Question 16

condensation polymerisation

Answer 16

refers to the formation of a polymer, usually by the reaction of two different monomers, and in which a small molecule is also formed

Question 17

aromatic

Answer 17

(originally description of the smell of certain organic compounds)
now… description of the bonding in a compound - delocalised electrons forming pi bonds in a hydrocarbon ring

Question 18

halogen carrier

Answer 18

a catalyst that helps to introduce a halogen atom into a benzene ring

Question 19

basicity

Answer 19

… of a base is the extent to which it can donate a lone pair of electrons to the hydrogen atom of a water molecule

Question 20

addition-elimination

Answer 20

occurs when two molecules join together, followed by the loss of a small molecule

Question 21

isoelectric point

Answer 21

of an amino acid is the pH of an aqueous solution in which it is neutral

Question 22

zwitterion

Answer 22

is a molecule containing positive and negative charges but which has no overall charge

Question 23

peptide bond

Answer 23

bond formed by a condensation reaction between the carbonyl group of one amino acid and the amino group of another amino acid

Question 24

hazard

Answer 24

a property of a substance that could cause harm to a user

Question 25

risk

Answer 25

the possible effect that a substance may cause to the user, and this will depend on factors such as the concentration and apparatus. the level of risk is controlled using control measures