AQA A-Level Chemistry AS Paper 1, November 2021: Question 18

1 mark · Easy difficulty · Multiple Choice

Identify which element in Period 3 has the highest melting point from the given multiple-choice options.

Practise this question

Question

Multiple choice question numbered 18 asking 'Which element in Period 3 has the highest melting point?' worth [1 mark]. The options are A Aluminium, B Silicon, C Sodium, and D Sulfur, each with an oval check box next to it.
Question text

18 Which element in Period 3 has the highest melting point?

[1 mark]

A Aluminium

B Silicon

C Sodium

D Sulfur

Mark scheme

Show the mark scheme Mark scheme indicating question 18 answer is B, corresponding to 1 mark for Silicon.

18 B 1 Silicon

How to answer it

Period 3 Melting Points Challenge

Question 18 • 1 Mark

What this question tests

This question assesses your understanding of physical properties across Period 3, specifically how the trends in melting points relate to bonding and structure types (metallic, giant covalent, and simple molecular).

Question Part 18

Identifying the Element with the Highest Melting Point

✅ Correct Answer

B: Silicon (Si)

Mark Awarded: 1 / 1 for selecting option B.

💡 Key Knowledge

  • Sodium to Aluminium: Metallic bonding. Melting point increases due to stronger electrostatic attraction from higher nuclear charge and more delocalised electrons per ion.
  • Silicon: Giant covalent macromolecular structure. Requires a massive amount of thermal energy to break the strong covalent bonds throughout the lattice.
  • Phosphorus, Sulfur, Chlorine, Argon: Simple molecular structures held together only by weak van der Waals forces, resulting in much lower melting points.

🧠 Exam Technique

Visualise or quickly sketch the trend in your head. Remember the sharp peak at silicon caused by its giant covalent structure, which far exceeds the melting points of the preceding metallic lattice elements and subsequent molecular gases/solids.

❌ Common Errors

  • Assuming the melting point increases steadily all the way across the period (mistakenly choosing sulfur or aluminium).
  • Confusing electrical conductivity trends (where silicon is a semiconductor and aluminium is a very good conductor) with melting point magnitude.

Topics

Inorganic Chemistry · 3.2.1 Periodicity

Question and mark scheme from the AQA A-Level Chemistry examination, AS Paper 1, November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.