Chemistry Paper 1 Exam Questions Wrong Answers

Question 1

Why are group 1 metals called alkali metals? (2 marks)

Answer 1

because they form hydroxides
1
that give alkaline solutions (in water)

Question 2

The alkali metals are in Group 1 of the Periodic Table. State what is formed when any alkali metal reacts with water.

Answer 2

any two from:
• hydrogen or H2
do not accept gas given off or fizzes
• heat
accept exothermic
do not accept flame
• alkaline solution
accept (metal) hydroxide or NaOH or OH–
do not accept dissolves or forms a solution or floating
accept balanced chemical equation for 2 marks
2

Question 3

Explain how the diameter of the atom affects the reactivity of Group 1 elements. (4 marks )

Answer 3

as diameter increases, reactivity increases
1
(because as diameter increases) outer electron is further from the nucleus
allow (because as diameter increases) outer shell is further from nucleus
1
(so) outer electron is less attracted to the nucleus
allow (so there is) increased shielding
1
(so) outer electron is lost (more) easily
1

Question 4

Copper and potassium have different melting points and boiling points.
Give one other difference between the properties of copper and potassium.
(4)

Answer 4

any one from:
• copper has a higher density
• copper is stronger
• copper is harder
• copper is less reactive
allow named property
ignore colour, conductivity, melting point and boiling point
allow converse for potassium

Question 5

Explain why group 1 metals are called alkali metals?

Answer 5

They react with water producing an alkaline solution

Question 6

Hydrogen is an element which is difficult to fit into a suitable position in the Periodic Table. Give reasons why hydrogen could be placed in either Group 1 or Group 7.

Answer 6

H+ or has positive ions/one electron in outer shell/can lose
one electron/H+ ions discharged at negative electrode (max 2)
covalent bonds or compounds/forms diatomic mols. or example/
ability to form H- ions/non-conductor/
low Mt.Pt or low B.P. (max 2)

Question 7

C2 Ionic bonding

Question 8

Explain why diamond has a high melting point

Answer 8

covalent bonds
1
giant structure / macromolecule
allow each C has 4 bonds
allow giant covalent structure for 2 marks
allow giant ionic / lattice structure for 1 mark
ignore lattice
1
lots of energy needed to break / overcome
allow disrupt structure
ignore heat and high temperature
if no other marks awarded allow 1 mark for strong / many bonds

Question 9

Explain the conditions needed for sodium chloride to conduct electricity.

Answer 9

dissolved (in water) or aqueous
allow in solution
1
molten / liquid
1
so ions are mobile or free moving
1
max 2 for incorrect reference to particles or bonds

Question 10

Describe how sodium conducts thermal energy (3 marks)

Answer 10

delocalised electrons (from outer shell)
1
(free to) move
1
energy transferred (through structure)
ignore conducts thermal energy
ignore electricity
if no other mark awarded allow 1 mark for ions / atoms vibrate

Question 11

Explain why chlorine (Cl2) is a gas at room temperature, but sodium chloride (NaCl) is a solid at room temperature. Include a description of the bonding and structure of chlorine and sodium chloride in your answer.

Answer 11

Chlorine:
covalent bonds between atoms
forming (simple) molecules
no / weak attraction / bonds between molecules
low boiling point
Sodium chloride:
ionic bonds or electrostatic attraction
strong bonds
in all directions
between oppositely charged ions
forming giant lattice
large amounts of energy needed to break bonds
high melting point

Question 12

Hot sodium is put in a gas jar of chlorine.
Describe the observations made before, during and after the reaction.

Answer 12

before)
silver solid / liquid / metal
allow grey solid / metal
or
green (gas)
allow yellow (gas)
1
(during)
yellow flame
allow orange / white flame
or
white smoke
or
green colour fades / disappears
1
allow vigorous reaction
(after)
white solid / powder

Question 13

Chlorine reacts with sodium and with hydrogen.
Compare the structure and bonding in sodium chloride and hydrogen chloride.
- look at ms

Answer 13

ndicative content

sodium chloride
hydrogen chloride
differences in bonding
ionic
covalent
metal & non-metal
two non-metals
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transferring electrons
sharing electrons
ions (Na+ and Cl– )
molecules
charged particles
neutral or no overall charge
differences in structure
giant structure or lattice
small / simple / discrete molecules
electrostatic
intermolecular forces
(electrostatic forces) are strong
(intermolecular forces) are weak
act in all directions
random or between the molecules
regular
irregular / random
similarities in bonding
full shells or stability
full shells or stability
(transferring) electrons
(sharing) electrons
strong bonds
strong (covalent) bonds
act in all directions
random or between the molecules
similarities in structure
(electrostatic) forces
(intermolecular) forces
ignore properties eg melting points, conduct electricity
to access level 2 there must be a comparison of the structure and bonding and magnitude of both sodium chloride and hydrogen chloride.

Question 14

Explain why magnesium chloride must be molten or dissolved in water to be electrolysed. (2 marks)

Answer 14

because ions can move
ignore ions attracted
do not accept molecules / atoms moving
do not accept incorrect reference to electrons moving
1
Page 29 of 37

(and ions move) to the electrodes
or
(and ions) carry charge
1
accept converse for solid

Question 15

Describe the structure and bonding in sodium chloride.

Answer 15

lattice / giant structure
max 3 if incorrect structure or bonding or particles
1
ionic or (contains) ions
1
Na+ and Cl-
Page 30 of 37

accept in words or dot and cross diagram: must include type and magnitude of charge for each ion
1
electrostatic attraction

allow attraction between opposite charges

Question 16

Many people do not have enough iodine in their diet.

Sodium chloride is added to many types of food. Some scientists recommend that sodium chloride should have a compound of iodine added.

Give one ethical reason why a compound of iodine should not be added to sodium chloride used in food.

Answer 16

any one from, eg:
*people should have the right to choose
*insufficient evidence of effect on individuals
*individuals may need different amounts.
allow too much could be harmful
ignore religious reasons
ignore cost
ignore reference to allergies

Question 17

Explain why iodine has a low melting point.

Answer 17

simple molecules
max 2 if incorrect structure or bonding or particles
accept small molecules
accept simple / small molecular structure
1
with intermolecular forces
accept forces between molecules
must be no contradictory particles
1
which are weak or which require little energy to overcome − must be linked to second marking point
reference to weak covalent bonds negates second and third marking points

Question 18

Explain, in terms of particles, why liquid iodine does not conduct electricity.

Answer 18

iodine has no delocalised / free / mobile electrons or ions
1
so cannot carry charge

Question 19

Explain why a high temperature is needed to melt potassium iodide. (3 marks)

Answer 19

attractions / forces (of attraction) / bonds are strong or lot of energy needed to break bonds / forces / attractions
Page 32 of 37

max 2 if reference to incorrect bonding or incorrect structure or incorrect particles
1
because oppositely charged ions attract or electrostatic attraction between ions
1
in giant structure or lattice
ignore many bonds
ignore ionic bonding unqualified
1

Question 20

Magnesium oxide is a white solid with a high melting point.
Explain how the ions are held together in solid magnesium oxide.
(2 marks)

Answer 20

oppositely charged (ions / atoms)
allow positive and negative(ions / atoms)
1
(they) attract

Question 21

C1 History of the periodic table

Question 22

Suggest why scientists in 1800 could not extract aluminium from alumina.

Answer 22

any one from:
*no method / electrolysis / equipment / technology
allow ‘didn’t know how to’ or ‘no knowledge’
*aluminium is a very reactive metal
*high melting point
allow ‘couldn’t heat it enough’
*potassium had not been discovered
1

Question 23

who discovered that electrons orbit the nucleus?

Answer 23

Niels Bohr

Question 24

Give one example of a pair of elements that would be placed incorrectly if they were in the order of their relative atomic masses.

Answer 24

argon and potassium or tellurium and iodine or cobalt and nickel
accept correct symbols allow argon and calcium

Question 25

Suggest two reasons why other scientists in 1871 did not accept Mendeleev’s periodic table.

Answer 25

any two sensible ideas such as:
* (why) put in order of mass
accept other equally valid orders, eg alphabetical
* he left gaps or table not complete
* no evidence for undiscovered elementsor they believed all the elementshad been discovered
accept predictions could not be backed by evidence accept why change previous ideas
* he changed the order of some elements or there were exceptions to the rule(s)
* he put metals and non-metals together
accept they didn’t like his groupings / groups
* he did not explain his ideas clearly (owtte)
do not accept modern explanations, eg proton number etc

Question 26

Why did Mendeleev leave gaps for undiscovered elements in his periodic table?

Answer 26

so that elements with similar properties could be placed together
allow to make the pattern fit
ignore undiscovered elements

Question 27

Lithium, sodium and potassium are all in Group 1 of the modern periodic table.
Explain why.

Answer 27

all have one electron in the outer shell (highest energy level)
allow same number of electrons in the outer shell (highest energy level)
1
(so they) have similar properties
or
react in the same way
allow specific reactions e.g. with water

Question 28

What evidence did Mendeleev use to decide that the alkali metals should be in the same group?

Answer 28

similar properties
allow same properties

Question 29

State two properties of transition elements that make them more useful than alkali metals for making water pipes.

Answer 29

any two from:
statements must be comparative
*stronger / harder
ignore higher densities
*less reactive
*higher melting points
ignore boiling point

Question 30

Suggest what predictions Mendeleev was able to make about these undiscovered elements.

Answer 30

predicted they were metals
allow atomic mass / weight
ignore atomic structure
1
predicted their (chemical/physical) properties / reactivity
accept any chemical / physical property
allow similar properties if mentioned in context of a group

Question 31

In Newlands’ periodic table, the elements lithium, sodium and potassium are grouped together.
Give two properties of these elements which support the idea that they should be grouped together.

Answer 31

any two from:
*react with water or very reactive
*(react with water) releasing gas / hydrogen / fizzing
*(react with water) to form an alkaline / hydroxide solution
*form ions with a 1+ charge
allow lose one electron from the outer shell
ignore other references to electronic structure
ignore physical properties

Question 32

Newlands’ periodic table was not accepted by most chemists in 1866.
Suggest reasons why.
- image

Answer 32

ome boxes contain two elements
allow specific examples:
Co, Ni or Ce, La or Di, Mo or Ro, Ru or Ba, V or Pt, Ir
*groups / columns contain elements with different properties
allow groups / columns contain both metals and non-metals
ignore examples
*Newlands not a well-known / respected scientist
ignore references to sugar factory
*new idea (not readily accepted by other scientists)
allow musical scales thought to be silly by some scientists

Question 33

State and explain one way in which Mendeleev improved Newlands’ periodic table.

Answer 33

one for improvement and one for explanation from:
*left gaps (for undiscovered elements) (1)
*so that elements were in their correct group (1)
allow so the elements fitted the pattern of properties
or
*did not always follow order of relative atomic weights / masses (1)
ignore references to atomic number / electronic structure
*so that elements were in their correct group (1)
allow so the elements fitted the pattern of properties

Question 34

In 1869 many chemists did not agree with Mendeleev’s periodic table.
Suggest three reasons why.

Answer 34

any three from:
ignore not enough evidence / proof or Mendeleev not respected
*(some) boxes had two elements
allow two correctly identified elements together (in the same box)
*Group 1: copper / silver unreactive (not like the others)
allow copper / silver not alkali metals / Group 1
*there are non-metals and metals in the same group / box
accept named examples
*Mendeleev left spaces / gaps
accept (some chemists thought) there were no more elements to discover
*Medeleev reversed the order (for some elements)

Question 35

How did Mendeleev know that there must be undiscovered elements and how did he take this into account when he designed his periodic table?

Answer 35

left gaps
1
if placed consecutively, then elements would be in wrong group / have wrong properties / owtte
Page 43 of 51

allow some elements didn’t fit pattern

Question 36

Transition elements have similar properties.
Explain why in terms of electronic structure.

Answer 36

(transition elements usually) have same / similar number of outer / 4thshell electrons
1
inner (3rd ) shell / energy level is being filled
ignore shells overlap

Question 37

There are no transition elements between the Group 2 element magnesium and the Group 3 element aluminium.
Explain why in terms of electronic structure.

Answer 37

2nd shell / energy level can (only) have maximum of 8 electrons
or
2nd shell / energy level cannot have 18 electrons

Question 38

In terms of properties, suggest why potassium (atomic weight 39) should be placed after argon (atomic weight 40).

Answer 38

potassium / it is an alkali metal or it is in group 1 or it is reactive
it = potassium
allow argon is a noble gas / unreactive / group 0

Question 39

In the 1890s a new group of elements (Group 0) was discovered.
Suggest why they were easily fitted into Mendeleev’s table.

Answer 39

it / they fitted at the beginning / end of the table
ignore left gaps / spaces

Question 40

What happens when a small piece of sodium reacts with water?You should describe what you would see and state what substances are formed. (3 marks)

Answer 40

maximum of 1 mark for descriptionfloats / surfacemay melt (not gets hot)moves aroundbubbles / steam / fumes / smoke / fizzdissolves / disappeared / gets smallerflame
(ignore sounds / heat)
any one for 1 mark
2 marks for correct product
sodium hydroxide or a solution containing sodium and hydroxide ions)NaOH / caustic soda hydrogen / H2(if more than 2 products given subtract one for each incorrect to maximum –2)
three for 1 mark each

Question 41

Explain why Mendeleev was able to predict the existence of francium in the 1870s. (2 marks)

Answer 41

Mendeleev arranged known elements in order of mass or properties
reject explanation in terms of electrons and / or atomic number
1
Page 49 of 51

gaps in Periodic Table / group 1

Question 42

Suggest why there is not much experimental evidence for the properties of francium (1 mark)

Answer 42

does not last long enough to experiment / very little of it
allow it has a short half-life

Question 43

If you could react francium with water, how would the reaction compare with that of sodium with water? (1 mark)

Answer 43

(much) more violent
accept more reactive

Question 44

C1 group 7 halogens

Question 45

In the early periodic tables some elements were placed in the wrong groups.
Mendeleev overcame this in his periodic table.
Give one way Mendeleev did this.

Answer 45

left gaps / spaces
or
changed the order based on atomic weights

Question 46

Explain the trend in boiling points down group 7?

Answer 46

(the) molecules get larger going down the group
1
(so the) forces between the molecules increase
or
(so the) intermolecular forces increase
1
(so the) boiling points increase going down the group
or
(so the) boiling points increase with increasing relative atomic mass
allow (so) more energy is needed to separate the molecules

Question 47

State why some elements were not placed in order of increasing atomic weight.

Answer 47

they would be in the wrong group / have the wrong / different properties/ don’t fit the pattern owtte
allow atomic weights may have been wrong

Question 48

The periodic table is now based on atomic structure.
Explain how. (3 marks)

Answer 48

any three from:
* elements arranged in proton / atomic number order
Page 27 of 39

ignore mass number / atomic weight / neutrons throughout
* group: elements in the same group / column havesame number of outer electrons owtte
* group: number of shells increase down group
* period: elements in the same period / row have the same number of shells / energy levels
* period: number of protons / electrons increase across period
* atomic number: link of atomic number to number of protons
* atomic number gives number of electrons

Question 49

Suggest why it is impossible to have an undiscovered element that would fit between sodium and magnesium. (1 mark)

Answer 49

it would mean splitting a proton / electron

Question 50

what state is bromine at 20 degrees celcius?

Answer 50

liquid

Question 51

Explain the trend in the melting points of the Group 7 elements.
Use Figure 2.

Answer 51

(the) molecules get larger going down the group
allow converse explanation in terms of melting point
allow atoms
allow from F to At
1
(so the) forces between the molecules increase
or
(so the) intermolecular forces increase
1
(so the) melting points increase going down the group
or
(so the) melting points increase with increasing relative atomic mass
allow (so) more energy is needed to separate the molecules

Question 52

Evaporation and boiling occur at the surface of bromine at its boiling point.
Name one more process that happens at the surface of bromine at its boiling point.

Answer 52

condensation

Question 53

Bromine reacts with sodium to produce sodium bromide.

(a)Describe the structure of and bonding in sodium bromide.
(2 marks)

Answer 53

giant structure of ions
1
with strong electrostatic forces of attraction

Question 54

The halogens are in Group 7 of the periodic table.
Explain the trend in reactivity of the halogens. ( 6 marks)

Answer 54

Simple statements / descriptions
*have 7 electrons in the outer shell
*need to gain an electron
*form ions with a -1 charge
*halogens further down the group are less reactive (or vice versa)
*halogens further down the group have more shells or energy levels (or vice versa)
Linked statements / explanations
*have 7 electrons in the outer shell so need to gain an electron to have the electronic structure of a noble gas
*halogens further down the group are less reactive because they have more shells or energy levels (or vice versa)
*halogens further down the group have more shells or energy levels so less attractive force on the incoming electron (or vice versa)
*halogens further down the group have more shells or energy levels so more ‘shielding’ against the incoming electron (or vice versa)
*outer electrons of halogens further down group are further away from the attractive force of the nucleus (or vice versa)
*an electron is less easily gained because there are more shells or energylevels (or vice versa)
*an electron is less easily gained because the outer electrons are further fromthe attractive force of the nucleus (or vice versa)

Question 55

Explain the arrangement of the first 20 elements in today’s periodic table.
Page 16 of 39

You should answer in terms of atomic structure.

Answer 55

arranged in order of atomic / proton number
1
elements in the same group have the same number of electrons in the outer shell

Question 56

Explain the order of reactivity of Group 7 elements.
Include information about atomic structure. (2 marks)

Answer 56

the further down the group, the halogen becomes less reactive because outer electrons are further from the nucleus

1

so less attractive force on an incoming electron

Question 57

which of the group 7 elements are solids at 20 degrees celcius?

Answer 57

Astatine and iodine

Question 58

Explain why fluorine is more reactive than chlorine. (4 marks)

Answer 58

gains an electron
more easily than Cl
because the higher the energy level
the less easily an electron is gained

each for 1 mark

Question 59

a) A chemist did an experiment to find out if fluorine reacts with xenon. The two gases were mixed in a glass container. The only product detected was silicon fluoride.
Explain what happened.
b) The experiment was repeated many years later but the gases were mixed in a different type of container.
A white solid was obtained which was xenon fluoride.

Predict whether you think (1) krypton and (2) radon will react with fluorine. Explain the reasons for your predictions.

Answer 59

a) fluorine reacted with silicon from glass

b) Reactivity increases down the group
radon likely to react because lower in group than xenon
more reactive than xenon
Kr may or may not react
higher in group than xenon
less reactive than xenon

Question 60

Explain why Group 0 elements are monatomic. (2 marks)

Question 61

is urea and glucose pure substances or mixtures?

Answer 61

pure substances