CCEA A Level Chemistry
CCEA A Level Chemistry 1.5 Structure Exam Questions
Free CCEA A Level Chemistry revision for 1.5 Structure: what you need to know, common mistakes and exam-style questions with answers. Covers giant ionic, metallic, giant covalent and simple molecular structures, their physical properties and the melting point trend across Period 3.
Practise 1.5 Structure with past papers
Once you have learnt this topic, find the 1.5 Structure questions in real CCEA A Level Chemistry past papers and mark them with the mark scheme. Doing lots of real questions is the quickest way to learn how examiners ask about each idea.
StemUp mark scheme flashcards
A-Level Chemistry Flashcards for 2027 Onwards
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Then test yourself with the questions on this page.
From £10.99View flashcards
About CCEA A Level Chemistry 1.5 Structure
Section 1.5 of Unit AS 1 links bonding to physical properties. You need to describe and draw the structures of sodium chloride (giant ionic), metals (metallic), diamond and graphite (giant covalent) and iodine (simple molecular), then explain melting and boiling points, hardness and electrical conductivity in terms of structure and bonding. CCEA also asks you to explain the trend in melting point across Period 3 from sodium to argon. This draws on bonding (1.3) and intermolecular forces (1.4). Examiners want precise language: which particles are present, what force holds them together and whether there are mobile charged particles.
What you need to know
- Giant ionic Sodium chloride has a lattice of Na+ and Cl- ions held by strong electrostatic attraction in all directions, each ion surrounded by six of the other. High melting point; conducts when molten or dissolved as ions are free to move.
- Metallic Positive ions in a sea of delocalised electrons. Conduct as solids because delocalised electrons move; malleable because layers of ions can slide.
- Giant covalent Diamond: each carbon bonded to four others tetrahedrally, very hard, very high melting point, no conduction. Graphite: each carbon bonded to three in hexagonal layers with delocalised electrons and weak forces between layers, so it conducts and is soft.
- Simple molecular Iodine is made of I2 molecules held in a lattice by weak van der Waals forces, so it has a low melting point and sublimes on warming.
- Period 3 trend Melting point rises from Na to Al (more delocalised electrons and smaller, higher charge ions), peaks at Si (giant covalent), then falls to P4, S8, Cl2 and Ar (simple molecular, van der Waals only; S8 is highest of these as it has the most electrons).
Common mistakes in 1.5 Structure
- Saying ionic compounds conduct as solids. Ions are fixed in the lattice; they conduct only when molten or in solution.
- Saying graphite conducts because of free ions. It conducts because of delocalised electrons between layers.
- Explaining the high melting point of silicon with intermolecular forces. Silicon is giant covalent, so many strong covalent bonds must be broken.
- Saying iodine has a low melting point because its covalent bonds are weak. The I-I bonds do not break; only van der Waals forces are overcome.
- Mixing up the sulfur and phosphorus order. S8 has more electrons than P4, so stronger van der Waals forces and a higher melting point.
Try three 1.5 Structure exam-style questions
1. Explain why sodium chloride has a high melting point. (2 marks)
Show the mark scheme answer
Giant ionic lattice; strong electrostatic attraction between oppositely charged ions needs a lot of energy to overcome.
2. Explain why graphite conducts electricity but diamond does not. (3 marks)
Show the mark scheme answer
In graphite each carbon forms three covalent bonds; one electron per carbon is delocalised and can move between layers; in diamond all four outer electrons are used in bonding so none are free.
3. Explain why aluminium has a higher melting point than sodium. (3 marks)
Show the mark scheme answer
Al3+ has a higher charge and smaller radius than Na+; Al contributes three delocalised electrons per atom; stronger metallic bonding requires more energy to overcome.
1.5 Structure FAQs
What does CCEA A Level Chemistry 1.5 Structure cover?
It covers giant ionic, metallic, giant covalent and simple molecular structures, how they explain physical properties, and the melting point trend across Period 3.
Which unit is 1.5 Structure examined in?
It is examined in Unit AS 1: Basic Concepts in Physical and Inorganic Chemistry, a 1 hour 30 minute paper with a multiple-choice section and structured questions. Related practical skills can also be assessed in Unit AS 3.
Which structures do I need to draw?
Learn to draw sodium chloride, diamond, graphite, a metallic lattice and iodine molecules, labelling the particles and the forces between them.
