02 Chemical Bonding, Set A To print: Ctrl + P, paper A4, margins Default.
Learners' AlleyDesigned by Khow Willard
02

Chemical Bonding

Set AFoundations
Name
Time 1 hour
Total 35 marks

A Data Booklet may be used.

A

From the lesson

11 marks
1
Explain why the melting point of potassium (63 °C) is lower than that of sodium (98 °C).
[2]

Source: Learners' Alley, Chemical Bonding slides

2
CommonExplain why NaF (993 °C) has a higher melting point than NaCl (801 °C).
[2]

Source: Learners' Alley, Chemical Bonding slides

3

State the shape and bond angle of

(a)
PCl3
[1]
(b)
SF6
[1]
(c)
XeF4
[1]

Source: Learners' Alley, Chemical Bonding slides

4
CommonExplain why SiO2 melts at 1710 °C but CO2 is a gas at room temperature.
[2]

Source: Learners' Alley, Chemical Bonding slides

5
Why is CO2 non-polar although the C=O bond is polar?
[1]

Source: Learners' Alley, Chemical Bonding slides

6
Why does ice float on water?
[1]

Source: Learners' Alley, Chemical Bonding slides

B

Practice

24 marks
7

CommonThe boiling point of water (100 °C) is greater than that of HF (20 °C). Which statement is a correct explanation of the above?

AEach hydrogen bond formed between water molecules is stronger than that formed between HF molecules.
BThere are more atoms in a water molecule than there are in an HF molecule, resulting in stronger intermolecular forces in water.
CThere are, on average, more hydrogen bonds between water molecules than there are between HF molecules.
DThe water molecule has stronger permanent dipole–dipole interactions than the HF molecule.
Answer [1]

Source: 2025 EJC J2 Prelim P1 Q4

8

The element tin exists in two forms, grey tin and white tin. Some properties of grey tin and white tin are shown.

grey tinwhite tin
boiling point2543 °C2533 °C
electrical conductivitynone in solid or liquidgood in solid and liquid
malleabilitybrittlemalleable

Which structural change might take place when grey tin changes to white tin?

Agiant covalent to giant ionic
Bgiant covalent to giant metallic
Cgiant ionic to giant covalent
Dgiant ionic to giant metallic
Answer [1]

Source: 2025 ASRJC J2 Prelim P1 Q4

9
Explain why sulfur can form sulfur hexafluoride but oxygen cannot form oxygen hexafluoride, though both elements are in the same group.
[2]

Source: EJC 2022 JC1 Chemical Bonding Tutorial, A3

10
(a)(i)
Describe the bonding present in solid krypton, 36Kr.
[1]
(ii)
Describe the bonding present in solid rubidium, 37Rb.
[1]
(b)
Use your descriptions of their bonding to explain why the boiling point of krypton is −152 °C whereas that of rubidium is 686 °C, despite their having nearly the same relative atomic mass, Ar.
[2]

Source: A Level 2017 P2 Q3, via EJC 2022 JC1 Chemical Bonding Tutorial, A12

11

CommonExplain each of the following observations as fully as you can in terms of chemical bonding and structure.

(a)
The boiling points of the halogens show a trend.
elementCl2Br2I2
boiling point / °C−35+59+184
[2]
(b)
Hydrogen fluoride has a higher boiling point than hydrogen chloride.
[2]
(c)
The boiling point of ammonia (−33 °C) is higher than that of phosphine, PH3 (−87 °C).
[2]

Source: EJC 2022 JC1 Chemical Bonding Tutorial, A13(a), (c) and (d)

12

CommonThis question is about the bond angles in some simple molecules.

(a)(i)
State the bond angle in a molecule of BF3.
[1]
(ii)
State whether the bond angle in NH3 is larger than, smaller than, or equal to that in BF3. Give an explanation for your answer.
[2]
(b)
Which of the species CH4 and NH3 has the larger bond angle? Give an explanation for your answer.
[2]

Source: RJC H2 Chemistry Tutorial 3a (Chemical Bonding I), Q4(a) and (b)

13
Both calcium oxide and sodium chloride have the same solid structure and similar ionic distances, yet calcium oxide melts at 2973 K whereas sodium chloride melts at 1074 K. Explain this observation in terms of structure and bonding.
[2]

Source: RJC H2 Chemistry Tutorial 3b (Chemical Bonding II), Q5(a)

14

ChallengeDichloromethane, CH2Cl2, is a solvent used to extract caffeine from coffee. Carbonated water contains H+ ions from carbonic acid.

(a)
Suggest whether the Cl–C–Cl bond angle in CH2Cl2 is smaller than, equal to, or larger than the H–C–H bond angle.
[1]
(b)
H+ ions do not exist in isolation in water. They bond to water molecules to form hydronium ions, H3O+. Predict and explain the shape of the hydronium ion.
[2]

Source: 2018 RI J1 Promo Section B Q3(d)(ii) and (e)(i)