The Periodic Table of Elements: Chemistry Tingkatan 4 questions

Section A: objective questions

12 marks

Choose the best answer for each question.

Which scientist arranged the elements in order of increasing proton number?

Dmitri Mendeleev
Henry Moseley
John Newlands
Lothar Meyer

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Moseley related X-ray spectra to proton numbers and arranged elements by proton number. Mendeleev and Newlands used atomic mass.

For the teacher: Remembering, low difficulty, standard 4.1.1

Textbook p. 81

An atom of element X has the electron arrangement 2.8.5. In which group and period is X?

Group 5, Period 3
Group 15, Period 5
Group 5, Period 8
Group 15, Period 3

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5 valence electrons gives Group 5 + 10 = 15. Three shells are filled, so Period 3.

For the teacher: Applying, low difficulty, standard 4.2.2

Textbook p. 83

Why is argon chemically unreactive?

It has one valence electron
It is a diatomic gas
Its valence shell is full with electrons
It has a large atomic radius

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Argon has a stable octet, so its atoms do not donate, accept or share electrons.

For the teacher: Understanding, low difficulty, standard 4.3.1

Textbook p. 85

Which noble gas is used to provide an inert atmosphere in high-temperature welding?

Argon
Helium
Neon
Radon

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Argon is used for an inert atmosphere in welding. Helium fills weather balloons, neon is used in advertising lights, radon treats cancer.

For the teacher: Remembering, low difficulty, standard 4.3.3

Textbook p. 86

Which property of Group 1 elements decreases down the group?

Atomic radius
Reactivity with water
Melting point
Number of shells

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Melting point falls (Li 186 °C, Na 98 °C, K 64 °C). Atomic radius, reactivity and number of shells increase.

For the teacher: Understanding, medium difficulty, standard 4.4.1

Textbook p. 88

Which equation correctly represents the reaction of potassium with water?

K + H₂O → KOH + H₂
K + 2H₂O → K(OH)₂ + H₂
2K + 2H₂O → 2KOH + H₂
2K + H₂O → K₂O + H₂

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Potassium forms K⁺, so the hydroxide is KOH. 2K + 2H₂O → 2KOH + H₂ is balanced (2 K, 4 H, 2 O on both sides).

For the teacher: Applying, medium difficulty, standard 4.4.2

Textbook p. 90

Why does reactivity decrease down Group 17?

The atoms lose electrons more easily
The valence shell is further from the nucleus, so the attraction on an incoming electron is weaker
The number of valence electrons decreases
The molecules become smaller

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Larger atoms attract an extra electron less strongly, so it is harder to fill the valence shell.

For the teacher: Analysing, medium difficulty, standard 4.5.3

Textbook p. 95

Which statement about elements across Period 3 from sodium to chlorine is correct?

Atomic radius increases
Electronegativity decreases
Number of shells filled with electrons increases
Atomic radius decreases

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The nuclear charge increases, pulling the electrons closer, so atomic radius decreases and electronegativity increases. The number of shells stays at 3.

For the teacher: Understanding, medium difficulty, standard 4.6.1

Textbook p. 97

Which oxide reacts with both nitric acid and sodium hydroxide solution?

Na₂O
MgO
Al₂O₃
SO₂

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Aluminium oxide is amphoteric. Na₂O and MgO are basic; SO₂ is acidic.

For the teacher: Applying, medium difficulty, standard 4.6.2

Textbook p. 99

Which of the following is NOT a special characteristic of transition elements?

Form coloured compounds
Have more than one oxidation number
Form complex ions
Form basic oxides that dissolve to give alkaline solutions

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Dissolving to give alkaline solutions is a property of Group 1 and 2 oxides. Transition elements form coloured ions, have variable oxidation numbers and form complex ions.

For the teacher: Understanding, medium difficulty, standard 4.7.2

Textbook p. 102

Rubidium (2.8.18.8.1) is more reactive than sodium (2.8.1) because its valence electron...

is further from the nucleus and is donated more easily
is held more strongly by the nucleus
is closer to the nucleus
is shared with another atom

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More filled shells mean a larger atom; the valence electron is further from the nucleus, the attraction is weaker and it is donated more easily.

For the teacher: Analysing, high difficulty, standard 4.4.3

Textbook p. 91

Element Y is in Period 4 and Group 2. What is its electron arrangement?

2.8.8.2
2.8.2
2.8.18.2
2.8.8.4

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Period 4 means four filled shells; Group 2 means two valence electrons. The arrangement is 2.8.8.2 (calcium).

For the teacher: Applying, high difficulty, standard 4.2.2

Textbook p. 83

Section B: structured questions

32 marks

Answer all questions. Write your answers in the spaces provided.

The proton numbers of four elements are: nitrogen 7, magnesium 12, sulphur 16 and argon 18.

[2 marks] (a)Write the electron arrangement of each of the four elements.

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N 2.5, Mg 2.8.2 [1]1
S 2.8.6, Ar 2.8.8 [1]1

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[2 marks] (b)State the group and the period of magnesium.

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Group 2 [1]1
Period 3 [1]1

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[2 marks] (c)State the group of sulphur and explain how you obtain it.

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Group 16 [1]1
6 valence electrons, 6 + 10 = 16 [1]1

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For the teacher: Applying, low difficulty, standard 4.2.2

Textbook p. 83

The boiling points of three Group 18 elements are: helium -269 °C, argon -186 °C and xenon -108 °C.

[1 mark] (a)State the trend in boiling point down Group 18.

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Boiling point increases down the group1

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[3 marks] (b)Explain the trend.

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Atomic size increases down the group [1]1
Attraction between atoms becomes stronger [1]1
More heat energy is needed to overcome it [1]1

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[2 marks] (c)Explain why helium is a monoatomic gas.

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It has a stable duplet arrangement / full valence shell [1]1
Its atoms do not donate, accept or share electrons [1]1

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For the teacher: Understanding, medium difficulty, standard 4.3.2

Textbook p. 85

Lithium, sodium and potassium are placed one at a time in water.

[2 marks] (a)Write a balanced chemical equation for the reaction of lithium with water.

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Correct formulae of reactants and products [1]1
2Li + 2H₂O → 2LiOH + H₂ (balanced) [1]1

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[1 mark] (b)State what happens to red litmus paper dipped in the solution formed.

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It turns blue1

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[1 mark] (c)Arrange lithium, sodium and potassium in order of increasing reactivity.

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Lithium, sodium, potassium1

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[3 marks] (d)Explain your answer to (c).

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Atomic size increases down the group (more shells) [1]1
Valence electron is further from the nucleus, so attraction is weaker [1]1
The electron is donated more easily [1]1

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For the teacher: Applying, medium difficulty, standard 4.4.2

Textbook p. 90

Fluorine, chlorine, bromine and iodine are Group 17 elements.

[1 mark] (a)Write the formula of the ion formed when a chlorine atom reacts.

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Cl⁻1

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[2 marks] (b)Write the equation for the reaction of iron with bromine to form iron(III) bromide.

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Correct formulae [1]1
2Fe + 3Br₂ → 2FeBr₃ [1]1

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[3 marks] (c)Explain why fluorine is more reactive than iodine.

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Fluorine atom is smaller [1]1
Valence shell is closer to the nucleus, so attraction on an incoming electron is stronger [1]1
It receives an electron more easily [1]1

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[1 mark] (d)State the state of matter of chlorine, bromine and iodine at room temperature.

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Chlorine gas, bromine liquid, iodine solid1

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For the teacher: Analysing, high difficulty, standard 4.5.3

Textbook p. 95

Iron is a transition element. Silicon is a metalloid used in electronic microchips.

[2 marks] (a)State the colour of the Fe²⁺ ion and the Fe³⁺ ion in solution.

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Fe²⁺ green [1]1
Fe³⁺ brown [1]1

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[2 marks] (b)State two other special characteristics of transition elements shown by iron.

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More than one oxidation number (+2 and +3) [1]1
Acts as a catalyst / forms complex ions [1]1

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[2 marks] (c)Silicon, a metalloid, is used in microchips. Explain why it is chosen instead of a metal such as lithium.

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Silicon is a semiconductor, a poor conductor at room temperature but a good conductor at high temperature [1]1
A metal like lithium conducts electricity well at all temperatures, so it cannot control the current [1]1

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For the teacher: Evaluating, high difficulty, standard 4.7.2

Textbook p. 102

Section A: objective questions

Question 1

Question 2

Question 3

Question 4

Question 5

Question 6

Question 7

Question 8

Question 9

Question 10

Question 11

Question 12

Section B: structured questions

Question 13

Question 14

Question 15

Question 16

Question 17