Solutions

Final test: Edexcel C2 topic 2 & 3 Structure and bonding (15 marks)

Which of the following is not a compound? (circle the correct answer)

  1. Water
  2. Oxygen
  3. Sodium chloride
  4. Methane

(1 mark)

  1. When fluorine, atomic number 9, reacts it forms a fluoride ion. Draw the structure of a fluoride ion and show the charge on it.

1 mark for electron arrangement (full outer shell, ignore dots/ crosses)

1 mark for negative charge shown (with or without brackets)

(2 marks)

  1. Ammonia is a compound made from nitrogen and hydrogen. Ammonia is a gas at room temperature. State the type of bonding present in ammonia and draw a diagram to show the bonding.

Bonding in ammonia: ………(simple) Covalent……. (1 mark)

1 mark for 3 hydrogen atoms bonded to nitrogen

1 mark for indication of shared electrons

1 mark for correct number of electrons on nitrogen outer shell

(4 marks)

  1. When elements react together they form new chemical ……bonds………. These form when the elements

share or exchange ………electrons…….

(2 marks)

  1. QWC: Here is some information about the oxides of two elements in the same group of the periodic table.

Carbon dioxide / Silicon oxide
Melting point: -78oC / Melting point: 1710oC
Boiling point: -57oC / Boiling point: 2230oC
Does not conduct electricity / Does not conduct electricity

Use the information in the table and your knowledge of structure and bonding to explain the similarities and the differences between the properties of carbon dioxide and silicon dioxide.

(6 marks)

QWC Suggested marking guidance (Total 6 marks)
Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Teachers should and apply a ‘best-fit’ approach to the marking.
0 marks / Level 1 (1-2 marks) / Level 2 (3-4 marks) / Level 3 (5-6 marks)
No relevant content. / One similarity or difference discussed.
The spelling, punctuation and grammar are very weak. / One similarity and difference discussed.
There is reasonable accuracy in spelling, punctuation and grammar, although there may still be some errors / Similarities and differences fully discussed and explained.
The answer shows almost faultless spelling, punctuation and grammar.
  • Covalent bonding (in both).
  • No electrons or ions available to conduct electricity (in either).
  • Carbon dioxide has a simple structure / carbon dioxide molecule or is molecular
  • Contains a small number of atoms / is a small molecule.
  • Silicon dioxide has a giant (covalent)structure / structure of silicon dioxide contains many atoms bonded together / 3D / lattice.
  • (All) atoms in silicon dioxide held together by strong bonds.
  • Bonds require large amounts of energy/heat to break.
  • Weak forces between molecules in carbon dioxide / forces do not require large amounts of energy/heat to break
  • Carbon dioxide has double bonds.
  • Silicon dioxide had only single bonds.
  • Each silicon atom is bonded to four oxygen atoms in silicon dioxide / is a tetrahedral structure.
  • Each carbon atom is bonded to two oxygen atoms in carbon dioxide.

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