GCSE Chemistry Diagnostic Assessment

Name:

Date:

Section 1: Atoms, the Periodic Table and Bonding

WALT: We are learning to identify strengths and gaps in GCSE Chemistry knowledge.

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1. [2 marks] Which statement about an atom is correct?

Electrons are found in the nucleus.

Protons have a negative charge.

Neutrons have no charge.

The atomic number is the number of neutrons.

2. [3 marks] An atom has 11 protons, 12 neutrons and 11 electrons.

a) What is its mass number? _________

b) What is its atomic number? _________

c) Explain why the atom has no overall charge.

3. [3 marks] Explain why metals conduct electricity but simple molecular substances usually do not.

4. [2 marks] Magnesium reacts with oxygen to form magnesium oxide. Complete and balance the symbol equation.

____ Mg + ____ O₂ → ____ MgO

Section 2: Chemical Changes, Quantitative Chemistry, Energy and Rates

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5. [3 marks] 25.0 cm³ of sodium hydroxide reacts with hydrochloric acid. The concentration of sodium hydroxide is 0.20 mol/dm³. Calculate the amount, in moles, of sodium hydroxide used. Show your working.

Use: amount = concentration × volume in dm³.

6. [3 marks] A student adds magnesium ribbon to dilute hydrochloric acid.

a) Name the gas produced. ____________________

b) Describe a test for this gas and the positive result.

c) Write the word equation.

magnesium + hydrochloric acid → ____________________ + ____________________

7. [3 marks] The temperature falls when two solutions react. Is this reaction exothermic or endothermic? Explain your answer in terms of energy transfer.

8. [3 marks] A reaction produces 60 cm³ of gas in 30 seconds. Calculate the mean rate of reaction in cm³/s. State one way to increase the rate.

Section 3: Organic Chemistry, Analysis, Atmosphere and Resources

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9. [2 marks] Which statement about crude oil is correct?

It is a pure substance with one boiling point.

It is separated into fractions by fractional distillation.

It is made only of oxygen and hydrogen.

It is a renewable resource.

10. [4 marks] A colourless solution is tested. Adding silver nitrate solution produces a cream precipitate. Identify the ion present and describe the test result. Explain why instrumental methods such as chromatography can be useful in chemical analysis.

11. [2 marks] State one human activity that increases carbon dioxide in the atmosphere and one possible effect of increased greenhouse gases.

12. [3 marks] Extended response: Explain why recycling metals can reduce environmental impact compared with extracting metals from ores. Include energy use and natural resources in your answer.

Final student reflection

My strongest topic is: ________________________________________________

The topic I need to revisit is: _________________________________________

One question I still have is:

Teacher answer key and diagnostic notes

Section 1: 1. Neutrons have no charge. 2. a) 23 b) 11 c) Equal numbers of positive protons and negative electrons. 3. Metals contain delocalised electrons that can move; simple molecular substances do not have freely moving charged particles. 4. 2Mg + O₂ → 2MgO.

Misconceptions to check: Confusing atomic number with mass number; thinking electrons are in the nucleus; believing all substances conduct electricity; incorrect balancing of formula equations.

Section 2: 5. 25.0 cm³ = 0.0250 dm³; amount = 0.20 × 0.0250 = 0.0050 mol. 6. a) Hydrogen b) A lit splint gives a squeaky pop c) magnesium + hydrochloric acid → magnesium chloride + hydrogen. 7. Endothermic; energy is taken in from the surroundings, causing the temperature to fall. 8. Rate = 60 ÷ 30 = 2 cm³/s; acceptable answers include increasing temperature or concentration, using a catalyst, or increasing surface area.

Misconceptions to check: Failure to convert cm³ to dm³; confusing hydrogen and oxygen tests; confusing exothermic and endothermic reactions; giving a factor that does not increase collision frequency or energy.

Section 3: 9. It is separated into fractions by fractional distillation. 10. Chloride ions; a cream precipitate forms with silver nitrate solution. Chromatography can separate and identify substances, often accurately and using small samples. 11. Burning fossil fuels; possible effects include global temperature rise, changing weather patterns or sea-level rise. 12. Recycling reduces mining and use of finite ores, usually uses less energy than extraction, and reduces waste and environmental damage.

Misconceptions to check: Confusing crude oil with a single compound; misidentifying halide precipitates; treating climate change and ozone depletion as the same issue; overlooking the energy and resource benefits of recycling.

Total score: ______ / 30