Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Covalent Bonding
68 practice questions
Topics covered
Practice questions
1–10 of 28 · Normal
Question 1
2 marks · Normal
Answer and see the solution →State what is meant by a covalent bond. Explain the mechanism by which a covalent bond forms between two atoms.
Question 2
4 marks · Normal
Answer and see the solution →(a)[2 marks]Draw a dot-and-cross diagram to show the covalent bonding in a molecule of ammonia (NH).
(b)[2 marks]State the number of bonding pairs and lone pairs of electrons on the nitrogen atom in ammonia.
Question 3
3 marks · Normal
Answer and see the solution →Ethene (CH) is an organic molecule. Explain, using electron arrangement, how you can use a dot-and-cross diagram to confirm that each atom in ethene has a full outer shell.
Question 4
4 marks · Normal
Answer and see the solution →Table 1. Molecules and their covalent bonds Molecule Number of Covalent Bonds per Molecule H2 1 CH4 4 NH3 3 CO2 4 Using the data in Table 1, answer the following questions:
(a)[1 mark]Which molecule contains the greatest number of covalent bonds per molecule?
(b)[2 marks]Explain why CO has four covalent bonds per molecule.
(c)[1 mark]State how many covalent bonds exist in two molecules of ammonia (NH).
Question 5
1 mark · Normal
Answer and check →Which of the following dot-and-cross diagrams correctly represents the covalent bonding in a molecule of hydrogen chloride, HCl?
- A.A. H and Cl with one shared pair and Cl with 6 additional outer electrons.
- B.B. H and Cl with one shared pair and Cl with only 2 outer electrons.
- C.C. H and Cl with two shared pairs between them.
- D.D. H atom with two electrons, Cl atom with seven electrons, but none shared.
Question 6
2 marks · Normal
Answer and see the solution →Describe what happens to the electrons in the outer shells of two hydrogen atoms when they form a molecule of hydrogen, H.
Question 7
4 marks · Normal
Answer and see the solution →(a)[2 marks]Draw a dot-and-cross diagram to show the covalent bonding in an oxygen (O) molecule.
(b)[2 marks]Explain why there are two covalent bonds between the two oxygen atoms.
Question 8
3 marks · Normal
Answer and see the solution →A molecule of ammonia () is formed by nitrogen bonding covalently with three hydrogen atoms.
Given that each covalent bond is formed by the sharing of one pair of electrons, calculate the total number of electrons that nitrogen shares with hydrogen in ammonia.
Question 9
2 marks · Normal
Answer and see the solution →State two characteristic physical properties of substances with simple molecular structures and explain why they have these properties.
Question 10
4 marks · Normal
Answer and see the solution →The table shows the relative molecular mass and boiling points for two gaseous substances:
Gases and their boiling points Substance Relative molecular mass (Mr) Boiling point (°C) Methane 16 –161 Sulfur hexafluoride 146 –64 (a)[2 marks]Explain why both methane and sulfur hexafluoride are gases at room temperature despite having different molecular masses.
(b)[2 marks]Explain how increasing the molecular mass affects the boiling point of simple molecular substances, using these examples.