PeriodicityAQA A-Level Chemistry: Topic test

20 questions, 54 marks

AQA A-Level Chemistry

Periodicity topic test

Total 54 marks

Name

Class

Date

1
A geologist analysing a mineral sample detects four elements, identified only by their proton numbers: 37, 49, 63 and 74.
(a)
Which of these elements is in the d block?
[1 mark]
AThe element with proton number 37
BThe element with proton number 49
CThe element with proton number 63
DThe element with proton number 74
(b)
In which subshell is the highest-energy electron of the element with proton number 49 found?
[1 mark]
A4d
B5s
C5p
D5d
(c)
The elements with proton numbers 37 and 63 are classified as s-block and f-block elements respectively. Explain what this classification means.
[2 marks]
Total for question 1: 4 marks
2
Aluminium is used in overhead power cables and silicon in microchips. Argon is used to fill some light bulbs. The melting points are: aluminium 933 K, silicon 1687 K and argon 84 K.
(a)
Which statement best explains why silicon has a much higher melting point than argon?
[1 mark]
AMany strong covalent bonds throughout the giant lattice must be broken
BSilicon atoms have much stronger London forces between them than argon atoms
CSilicon has strong attraction between positive ions and delocalised electrons
DSilicon exists as Si₈ molecules with strong covalent bonds between the molecules
(b)
Which statement best explains why the first ionisation energy of argon is greater than that of aluminium?
[1 mark]
AArgon has a larger atomic radius than aluminium
BArgon has more protons, and its outer electrons are in the same shell with similar shielding
CArgon has more inner shells, so its outer electron is better shielded
DArgon has its outer electron in the 3s subshell
(c)
Explain why the melting point of aluminium is much lower than that of silicon.
[2 marks]
Total for question 2: 4 marks
3
A chemist is told that an unknown element has the electron configuration [Kr]4d¹⁰5s²5p², where [Kr] represents the 36 electrons of a krypton atom. She then compares its position in the periodic table with silicon (proton number 14) and sodium (proton number 11) in Period 3.
(a)
Deduce the proton number of the unknown element and state its block. Explain your answers.
[3 marks]
(b)
Explain why the atomic radius of silicon is smaller than that of sodium, and why the first ionisation energy of silicon is greater than that of sodium.
[4 marks]
Total for question 3: 7 marks
4
A student studies four Period 3 elements: magnesium, silicon, phosphorus (as white phosphorus, P₄) and argon, with proton numbers 12, 14, 15 and 18.
(a)
State the block of each element. Explain, in terms of structure and bonding, why the melting points decrease in the order silicon > magnesium > phosphorus > argon.
[6 marks]
(b)
The student states: 'First ionisation energy increases steadily across Period 3 because atomic radius decreases steadily.' Evaluate this statement, referring to magnesium and aluminium and to phosphorus and sulfur.
[6 marks]
Total for question 4: 12 marks
5
A student is given two electron configurations from a data book. Element G is [Ar]3d¹⁰4s²4p¹ and element H is [Xe]4f¹⁴5d²6s².
(a)
In which block is element H found?
[1 mark]
As block
Bd block
Cf block
Dp block
(b)
What is the proton number of element G?
[1 mark]
A31
B13
C30
D33
(c)
Explain why the position of an element in the periodic table is determined by its proton number rather than by its relative atomic mass.
[2 marks]
Total for question 5: 4 marks
6
Sodium, chlorine and argon are compared in a lesson on Period 3. Sodium has 11 protons, chlorine 17 and argon 18. At room temperature sodium is a metal that melts at 371 K, chlorine exists as Cl₂ molecules that melt at 172 K, and argon exists as single atoms that melt at 84 K.
(a)
Why is the atomic radius of a chlorine atom smaller than that of a sodium atom?
[1 mark]
AChlorine atoms have fewer occupied shells
BChlorine atoms have more shielding electrons
CChlorine atoms have a greater nuclear charge and similar shielding
DChlorine atoms have lost an electron
(b)
Which statement explains why argon has a lower melting point than chlorine?
[1 mark]
AArgon has covalent bonds that are weaker than those in chlorine
BArgon has metallic bonding that is weaker than in chlorine
CArgon atoms have stronger London forces than chlorine molecules
DArgon atoms have fewer electrons, so the London forces between them are weaker
(c)
Explain why sodium has a much higher melting point than chlorine.
[2 marks]
Total for question 6: 4 marks
7
A teacher gives students the proton numbers of two Period 3 elements, magnesium (12) and aluminium (13), and asks them to work out their positions in the periodic table and compare their first ionisation energies.
(a)
Write the full electron configurations of magnesium and aluminium and state the block of each element.
[3 marks]
(b)
Use the electron configurations to explain why the first ionisation energy of aluminium is lower than that of magnesium, even though aluminium has more protons.
[4 marks]
Total for question 7: 7 marks
8
In 1869 Mendeleev arranged elements mainly by relative atomic mass. The modern table is arranged by proton number. Argon (proton number 18, relative atomic mass 39.95) and potassium (proton number 19, relative atomic mass 39.10) show the difference. Sodium melts at 371 K, silicon at 1687 K and argon at 84 K.
(a)
Explain why argon comes before potassium in the modern periodic table, and use the electron configurations of the two elements to state the block of each.
[6 marks]
(b)
A student says: 'Argon has the weakest bonding of these three elements because it has the lowest melting point.' Evaluate this statement by explaining the melting points of sodium, silicon and argon in terms of structure and bonding.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).