AQA GCSE Chemistry Chemistry Paper 1 (Higher), November 2021: Question 1

✅ Correct Answer

Spherical (or ball-shaped).

🧠 Exam Technique

Buckminsterfullerene (C₆₀) is a hollow sphere resembling a football made from pentagons and hexagons of carbon atoms.

❌ Common Errors

Do not write "round" or "circular". These describe two-dimensional circles, whereas fullerenes are three-dimensional spheres.

💡 Key Knowledge

Fullerenes are molecules of carbon atoms with hollow shapes based on hexagonal rings, but they can also contain rings of 5 or 7 carbon atoms.

✅ Acceptable Answers (Give ANY one)

• Drug delivery (into specific cells in the body)
• Lubricant (spherical molecules roll over each other)
• Catalysts (large surface area to volume ratio)
• Hydrogen storage
• Anti-oxidants
• Strengthening materials (carbon nanotubes)

❌ Common Errors

Vague answers like "for medicine" or "used in cars" do not gain credit. Be precise: specify "drug delivery" or "lubricant".

✅ Correct Answer

Add two carbon atoms bonded to the central C, each with 3 attached H atoms via single lines:

🧠 How to Check Your Drawing

Count the bonds on every atom:

• Each Carbon (C) must have exactly 4 lines (4 bonds).
• Each Hydrogen (H) must have exactly 1 line (1 bond).
• The Oxygen (O) already has a double bond (=) attached to the central C.

❌ Common Errors

Forgetting one of the end hydrogen atoms or drawing bonds directly between hydrogens and oxygen.

✅ Correct Answer

C₃H₆O (or CH₃COCH₃)

🧠 Systematic Counting

Look at the dot-and-cross diagram and count the chemical symbols:

• Carbon atoms (C): 1 left + 1 centre + 1 right = 3
• Hydrogen atoms (H): 3 left + 3 right = 6
• Oxygen atoms (O): 1 bottom = 1

❌ Common Errors

Writing charges or improper subscript formatting (e.g. C3H6O without subscripts, though examiners allow it if clearly intended, standard subscript format is expected). Mixing up hydrogen count by missing peripheral H circles.

✅ Correct Box

☑ The intermolecular forces are weak.

❌ Number One GCSE Misconception

Never tick "covalent bonds are weak"! Covalent bonds are extremely strong, but they do not break when propanone boils. Only the weak forces between molecules (intermolecular forces) are overcome.

💡 Part 1: Why Graphite Conducts Electricity

1. Graphite has a giant covalent structure.
2. Each carbon atom forms only three covalent bonds.
3. This leaves one delocalised electron per carbon atom.
4. These delocalised electrons are free to move through the layers.
5. They carry electrical charge through the structure.

💡 Part 2: Why Graphite is Soft and Slippery

1. Carbon atoms form layers of hexagonal rings.
2. There are weak intermolecular forces between the layers (no covalent bonds between layers).
3. Because these forces are weak, the layers can slide over each other easily.

🧠 Top-Level Structure (Full 6/6 Template)

Structure your answer into two distinct paragraphs using connective phrases:

"Graphite is an electrical conductor because each carbon atom forms 3 covalent bonds, leaving one electron per atom delocalised. These delocalised electrons can move throughout the structure carrying electric charge."

"Graphite is soft and slippery because it is arranged in layers of hexagonal rings with only weak forces between layers. This means the layers can easily slide over one another."

❌ Costly Mistakes to Avoid

• Saying "ions move": Graphite contains neutral carbon atoms and delocalised electrons, not ions!
• Saying "covalent bonds break": The covalent bonds within layers are very strong and do not break when graphite is rubbed.
• Covering only one property: If you only explain conduction, you are capped at Level 2 (max 4 marks). Always address both bullet points!