A2 Chemistry Definitions

Question 1

Acid-base pair

Answer 1

A pair of two species that turn into each other through either losing or gaining a proton

Question 2

Activation energy

Answer 2

The minimum level of energy needed to start a reaction by breaking bonds

Question 3

Addition polymer

Answer 3

A very long molecular chain that is formed by repeated addition reactions of many monomers (unsaturated alkene molecules)

Question 4

Addition reaction

Answer 4

A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule

Question 5

Adsorption

Answer 5

The process that occurs when a gas, liquid or solute is held to the surface of a solid or less commonly a liquid

Question 6

Alicyclic hydrocarbon

Answer 6

A hydrocarbon that has carbon atoms joined together in a ring formation

Question 7

Aliphatic hydrocarbon

Answer 7

A hydrocarbon that has carbon atoms joined together in either straight or branched chains

Question 8

Alkali

Answer 8

A type of base that dissolves in water to form hydroxide ions (OH-)

Question 9

Alkanes

Answer 9

The homologous series with the general formula CnH2n+2

Question 10

Alkyl group

Answer 10

An alkane with a hydrogen atom removed

Question 11

Amount of substance

Answer 11

The mole. The amount of substance is the means by which chemists can count atoms

Question 12

Anhydrous

Answer 12

A substance that contains no water molecules

Question 13

Anion

Answer 13

A negatively charged ion

Question 14

Atom economy

Answer 14

The molecular mass of the desired product divided by the sum of the molecular masses of all the products x100%

Question 15

Atomic number

Answer 15

The number of protons in the nucleus of an atom

Question 16

Atomic orbital

Answer 16

A region within an atom that can hold up to two electrons with opposite spins

Question 17

Avogadro’s constant (N A)

Answer 17

6.02 x10 23mol-1

Question 18

Biodegradable substance

Answer 18

A substance that can be broken down naturally in the environment by other living organisms

Question 19

Biodegradable polymer

Answer 19

A polymer that breaks down completely into CO2 and H2O

Question 20

Boltzmann distribution

Answer 20

A diagram that shows the distribution of the energies of the molecules at a particular temperature

Question 21

Bronsted-Lowry acid

Answer 21

A species that is a proton donor, H+

Question 22

Bronsted-Lowry base

Answer 22

A species that is a proton acceptor, H+

Question 23

Buffer solution

Answer 23

A substance that reduces the difference in pH when small volumes of either acid or base are added to a solution

Question 24

Carbanion

Answer 24

An organic ion in which a carbon atom has a negative charge

Question 25

Carbocation

Answer 25

An organic ion in which a carbon atom has a positive charge

Question 26

Catalyst

Answer 26

A substance that speeds up a chemical reaction without being used up itself

Question 27

Cation

Answer 27

A positively charged ion

Question 28

Chiral carbon

Answer 28

A carbon atom that is attached to four other different atoms or groups of atoms

Question 29

Complex ion

Answer 29

A transition metal ion bonded to one or more ligands by coordinate bonds

Question 30

Ligands

Answer 30

An ion or molecule that binds to a central metal atom to form a complex

Question 31

Coordinate bonds

Answer 31

A covalent bond in which both electrons come from the same atom. Also known as a dative bond.

Question 32

Concentration

Answer 32

The amount of solute in moles per 1000cm3 of solution

Question 33

Condensation reaction

Answer 33

A reaction where two small molecules react together to form a bigger molecule releasing small molecules such as water

Question 34

Conjugate base

Answer 34

A species formed when a proton is added to a base

Question 35

Conjugate acid

Answer 35

A species formed when a proton is added to an acid

Question 36

Coordination number

Answer 36

the total number of coordinate bonds that have formed between the central metal ion and any ligands

Question 37

Covalent bond

Answer 37

A bond formed by a shared pair of electrons

Question 38

Cracking

Answer 38

The breaking down of long chain saturated hydrocarbons to form a mixture of short chained alkenes and alkanes

Question 39

Curly arrow

Answer 39

A symbol used in reaction mechanisms to the movement of an electron pair during the breaking or formation of a covalent bond

Question 40

Dative covalent

Answer 40

A bond in which the pair of electrons are shared within the one atom only

Question 41

Degradable polymer

Answer 41

A polymer that breaks down into smaller pieces when exposed to light, heat or moisture

Question 42

Dehydration

Answer 42

An elimination reaction whereby water is removed from a saturated molecule to form an unsaturated molecule