Oxford Revise AQA GCSE Chemistry | Chapter C4 answers

C4: The Periodic Table

Question

Answers

Extra information

Mark

AO / Specification reference

01.1

metal

1

AO1

4.1.2.3

01.2

rubidium hydroxide and hydrogen

1

AO2

4.1.2.5

01.3

rubidium + oxygen → rubidium oxide

1

AO1

4.1.2.5

01.4

2Na(s) + Br2(l) → 2NaBr(s)

one mark for balancing

one mark for state symbols

2

AO2

4.1.2.5

01.5

rubidium is more reactive than sodium/sodium less reactive

because it is further down Group 1/it has more electron shells

outer electron is further from the nucleus / the nucleus is more shielded

so easier to transfer to bromine/easier to remove

1

1

1

1

AO1

4.1.2.5

02.1

gaps were left for elements that were predicted to exist, but had not yet been discovered

in some places, the order of the elements were changed (based on atomic weights)

1

1

AO1

4.1.2.2

02.2

elements could be arranged in order of atomic/proton number

so elements were grouped according to their chemical properties.

1

1

AO1

4.1.2.2

02.3

elements in the same group of the Periodic Table have the same number of electrons in their highest energy level/outer shell

number of electrons in the highest energy level/outer shell determine the chemical properties of an element

1

1

AO1

4.1.2.2

02.4

the existence of neutrons makes possible the existence of isotopes

1

AO2

4.1.2.2

03.1

Group 0: inert

Group 1: react with water to make alkaline solutions

Group 7: react with metals to make ionic compounds

one mark for each correct match

3

AO2

4.1.2.5

03.2

Level 3: Clearly links trend in reactivity for both groups to electron structure.

5-6

AO2

4.2.2.3

Level 2: Clearly links trend in reactivity for one group to electron structure OR correctly states trends in reactivity for both groups.

3-4

Level 1: Correctly states trends in reactivity for one/both groups.

1-2

No relevant content

0

Indicative content

  • Group 1 gets more reactive down the group
  • Group 1 loses outer electron to form full outer shell/nearest noble gas
  • electron is further from the nucleus, so becomes easier to remove
  • Group 7 gets less reactive down the group
  • Group 7 atoms gain electron to form full outer shell/nearest Noble Gas
  • less attraction felt by positive nucleus charge further away from nucleus.

03.3

inert/unreactive

because atoms already have a full outer electron shell

ignore references to heavier Noble Gases forming some compounds

1

1

AO1

4.1.2.4

04.1

outer electrons of xenon are far away from the nucleus

weaker electrostatic force between outer electrons and positively charged nucleus

strong attraction from the positively charged fluorine nucleus

1

1

1

AO3

4.1.2.4

4.1.2.6

04.2

Xe atom should have 8 black dots and 4 green dots. F atoms should have 8 black dots.

each F atoms should share 2 black dots with the Xe atom

2

AO3

4.2.1.4

04.3

covalent

1

AO1

4.2.1.4

05.1

Group 1

1

AO1

4.1.2.5

05.2

so that the big lump of sodium does not react with oxygen/water from the air

1

AO3

05.3

to avoid sodium reacting with water on fingers/to prevent injury to the hand

1

AO3

05.4

use filter paper to remove the oil from the surface of the sodium/scrape the surface of the sodium to expose the metal or remove some sodium oxide

1

AO3

05.5

hydrogen/H2.

reject H

1

AO1

4.1.2.5

05.6

add universal indicator to the water

colour change from green to blue/purple

allow other indicators provided correct colour change given

1

1

AO1

4.1.2.5

05.7

atoms of all Group 1 elements lose an electron in their reactions

atoms get bigger down the group, so the outer electron is further from the nucleus/Na has an extra shell/Li has one fewer shell

electrostatic force of attraction between positive nucleus and negatively charged electron decreases down the group

so it is easier to lose electron/transfer electron

allow references to shielding

one mark for each part of the explanation

3

AO1

4.1.2.5

5.8

very vigorous reaction/caesium catches fire/very vigorous bubbling

allow any correct observations

allow damage to glass trough answers only if they are related to the high reactivity of Cs

1

AO2

4.1.2.5

06

Level 3: Solutions X, Y and Z are correctly identified, and the justification is correct and explained coherently and logically.

5-6

AO3

4.1.2.6

Level 2: Solutions X, Y and Z are correctly identified, and some aspects of the justification are correct. The explanation lacks coherence and logic.

3-4

Level 1: One or two solutions are correctly identified, and one or two points of explanation are made. The explanation lacks coherence and logic.

1-2

No relevant content

0

Indicative content

  • X is potassium bromide, Y is potassium chloride, Z is potassium iodide
  • a Halogen displaces a less reactive Halogen from an aqueous solution of its salt
  • chlorine is more reactive than bromine, so chlorine displaces bromine from potassium bromide solution (solution X) and iodine from potassium iodide solution (solution Z)
  • bromine is more reactive than iodine, so bromine displaces iodine from potassium iodide solution (solution Z)
  • iodine is less reactive than both chlorine and bromine, so displaces neither of these compounds from solutions of their salts

07

Level 3: The prediction is correct, and the explanation is clear, coherent and logical.

5-6

AO1 × 5

AO3 × 1

4.1.2.5

4.1.2.6

Level 2: The prediction is correct, but the explanation lacks some clarity and coherence.

3-4

Level 1: The prediction is incorrect, but one or two aspects of the explanation are correct.

1-2

No relevant content

0

Indicative content:

  • D – sodium and fluorine
  • fluorine is most reactive of the Halogens given and sodium is most reactive of the Alkali Metals given
  • in the reaction, each fluorine atom gains an electron and each sodium atom loses an electron.
  • fluorine atom attracts electrons to it more strongly than bromine because its atoms are smaller
  • so incoming electrons are attracted to the nucleus more strongly
  • sodium loses its electrons more easily than lithium because its atoms are bigger
  • so the outer shell/highest energy level electrons are less strongly attracted to the nucleus

08.1

Noble Gases

1

AO1

4.1.2.4

08.2

A

1

AO2

4.1.2.4

08.3

A

1

AO2

4.1.2.4

08.4

Ne atom should have 2 rings with 2 dots on the first ring and 8 dots on the second ring

1

AO1

4.1.2.4

08.5

their atoms have a full outer shell of electrons/highest energy level/stable electron arrangement

1

AO2

4.1.2.4

09.1

B

1

AO2

4.1.2.1

09.2

C

because its outer electron shell/highest energy level is full/atoms have stable arrangement of electrons

1

1

AO2

4.1.2.4

09.3

A and D

both required for the mark

1

AO2

4.1.2.1

10.1

increases

because, like Group 1, atoms of Group 2 elements react by losing electrons

atoms get bigger down the group, so the outer electrons are further from the nucleus

so the force of attraction between the nucleus and the outer electrons decreases.

no mark for ‘increases’ alone

1

1

1

1

AO2 × 2

AO3 × 2

4.1.2.5

10.2

giant (metallic) structures

atoms arranged in regular pattern

electrons of outer shells of atoms delocalised and free to move throughout the whole structure

1

1

1

AO1

4.2.1.5

10.3

less

sodium reacts vigorously with cold water.

1

1

AO3

4.1.2.5

10.4

MgCl2

1

AO3

4.1.2.5

11.1

H atom should have 1 dot and 1 cross. F atom should have 7 crosses and 1 dot.

H atom and F atom should be sharing one dot and one electron.

2

AO2

4.1.2.6

4.2.1.4

11.2

Level 3: The electronic structures are correctly stated or drawn, and the explanation is clear, coherent and logical.

5-6

AO2

4.1.2.6

Level 2: The electronic structures are correctly stated or drawn, but the explanation lacks some clarity and coherence.

3-4

Level 1: One of the electronic structures are correctly stated or drawn, and one or two parts of an explanation are included.

1-2

No relevant content

0

Indicative content:

  • correctly stated or drawn electronic structures of fluorine (2,7) and chlorine (2,8,7) atoms
  • atoms of fluorine and chlorine gain an electron in their reactions.
  • chlorine is bigger than fluorine, so its outer electrons are

    further from nucleus

  • electrostatic force of attraction between positive nucleus and incoming negatively charged electron is greater for fluorine than chlorine

11.3

products of reaction three melts at higher temperature.

product of reaction two has small molecules/simple molecules, so low melting point

product of reaction three has (giant) ionic structure, so high melting point

one mark for correct suggestion, one mark for reason

1

1

1

AO2 × 2

AO3 × 1

4.1.2.6

12.1

Alkali Metals

1

AO1

4.1.2.6

12.2

they have the same number of electrons in the shell furthest from the nucleus

1

AO1

4.1.2.1

12.3

metals

1

AO1

4.1.2.3

12.4

caesium bromide

1

AO2

4.1.2.5

4.1.2.6

13.1

B

1

AO2

4.2.2.1

13.2

2,8,8

1

AO2

4.1.1.7

13.3

one electron from potassium’s outer shell

is transferred to chlorine’s outer shell

to form +1 potassium ion and -1 chlorine ion

electrostatic attraction occurs between oppositely charged ions

1

1

1

1

AO2

4.2.1.2

13.4

ions/charges are free to move

1

AO2

4.2.2.3

13.5

place solution in round-bottom flask

and attach this round-bottom flask to condenser

heat this round-bottom flask with a Bunsen burner

water will evaporate and condense in the condenser

this can be collected in a separate vessel.

potassium chloride will remain in the round-bottom flask.

1

1

1

1

1

1

AO1

4.1.1.2

14.1

discovery of neutrons led to discovery of isotopes

explained why atomic weight order was not correct

1

AO1

4.1.2.2

14.2

has one electron in the outermost shell.

does not share properties with the rest of Group 1 elements

accept a named property

1

1

AO3

4.1.2.5

14.3

number of protons

1

AO1

4.1.1.5

14.5

\(
\begin{array}{l}
{M_{\rm{R}}} = \frac{{(92.2 \times 28) + (4.7 \times 65) + (3.1 \times 30)}}{{100}}\\
=28.109\\
=28.1
\end{array}
\)

1

1

1

AO2

4.1.1.6

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