module 1

Question 1

isotope

Answer 1

atoms of the same element with different numbers of neutrons

Question 2

atomic n.o

Answer 2

number of protons in the nucleus of an atom

Question 3

mass n.o

Answer 3

number of particles (protons and neutrons) in the nucleus

Question 4

ion

Answer 4

positively or negatively charged atom

Question 5

relative isotopic mass

Answer 5

the mass of an isotope compared with 1/12 of the mass of an atom of carbon-12

Question 6

relative atomic mass Ar

Answer 6

the weighted mean mass of an atom of an element compared with 1/12 of an atom of carbon-12

Question 7

relative molecular mass Mr

Answer 7

the weighted mean mass of a molecule compared with 1/12 of an atom of carbon-12

Question 8

relative formula mass

Answer 8

the weighted mean mass of a formula unit (empirical formula) compared with 1/12 of the mass of an atom of carbon-12

Question 9

amount of substance

Answer 9

the quantity whose unit is the mole. ‘amount of substance’ is a means of counting atoms.

Question 10

the Avogadro constant Na

Answer 10

the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 mol^-1)

Question 11

mole

Answer 11

the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon 12 isotope.

Question 12

molar mass

Answer 12

the mass per mole of a substance g-mol^-1

Question 13

empirical formula

Answer 13

the simplest whole number ratio of atoms present in a compound

Question 14

molecule

Answer 14

a small group of atoms held together by covalent bonds

Question 15

the molecular formula

Answer 15

the actual number of atoms of each element in a molecule

Question 16

molar volume

Answer 16

this is the volume per mole of gas. dm^3 mol^-1
At rtp molar volume is 24.0 dm^3 mol^-1

volume(dm^3) = n.o moles x 24

volume(cm^3) = n.o moles x 24000

Question 17

concentration

Answer 17

the amount of solute in mol dissolved per 1dm^3 (1000cm^3) of solution.

Question 18

standard solution

Answer 18

a solution of known concentration. normally used in titrations to determine unknown information about another substance.

Question 19

species

Answer 19

a type of particle that takes place in a chemical reaction

Question 20

stochiochemistry

Answer 20

the molar relationship between relative quantities of substances taking part in a reaction

Question 21

acid

Answer 21

a species that is a proton donor

all acids contain hydrogen, when added to water, acids release this hydrogen as H+ ions (protons)

Question 22

base

Answer 22

a species that is a proton acceptor

Question 23

alkali

Answer 23

a base dissolved in water, forming hydroxide ions

NaOH(s) + aq —-> Na+ (aq) + OH- (aq)

e.g. NaOH, KOH, NH3

Question 24

salt

Answer 24

a chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion such as the ammonium ion NH4+

Question 25

cation

Answer 25

positively charged ion

Question 26

anion

Answer 26

negatively charged ion

Question 27

hydrated

Answer 27

refers to a crystalline compound containing water molecules

Question 28

anhydrous

Answer 28

refers to a substance that contains no water molecules

Question 29

water of crystallisation

Answer 29

refers to water molecules that form an essential part of the crystalline structure of a compound

Question 30

``` methyl orange colour changes: acid... base... neutral... ```

Answer 30

colour changes: acid. ..red base. ..yellow neutral. ..orange

Question 31

``` bromothymol blue colour changes: acid... base... neutral... ```

Answer 31

colour changes: acid. ..yellow base. ..blue neutral. ..green

Question 32

``` phenolphthalein colour changes: acid... base... neutral... ```

Answer 32

colour changes: acid. ..colourless base. ..pink neutral. ..pale pink

Question 33

oxidation number

Answer 33

a measure of the number of electrons that an atom uses to bond with atoms of another element

Question 34

oxidation

Answer 34

loss of electrons or increase in oxidation n.o

Question 35

reduction

Answer 35

a gain of electrons or decrease in oxidation n.o

Question 36

reducing agent

Answer 36

a reagent that reduces (adds electrons to) another species.

Question 37

oxidsing agent

Answer 37

a reagent that oxidises (takes electrons) from another species.