Year 8 Science • AC9S8U06 • Authored homework
Elements, Compounds and Mixtures
Classify matter using particles, symbols, formulas and simple separation ideas. Answer in full sentences where useful, and use evidence or examples in longer responses.
Part A
Short-answer questions
Define element.
Define compound.
Define mixture.
Explain the difference between a compound and a mixture.
Classify oxygen gas, pure water and seawater as element, compound or mixture.
What does a chemical formula show about a compound?
Why can a mixture often be separated by physical methods?
Give one example of a homogeneous mixture and one example of a heterogeneous mixture.
Explain why sodium chloride is not a mixture of sodium pieces and chlorine gas.
Write one particle-level sentence comparing an element and a compound.
Part B
Long-answer questions
Compare elements, compounds and mixtures using particle diagrams, composition and separation methods.
Explain why water is a compound but salt water is a mixture.
Describe how filtration, evaporation or chromatography could separate a mixture. Choose one method and explain why it works.
A student says, “All substances made of more than one atom are mixtures.” Evaluate this claim.
Use examples to explain the difference between chemical bonding in compounds and physical mixing in mixtures.
Interpret a particle diagram containing identical single atoms, identical bonded groups and different particles mixed together.
Explain why symbols such as O, Fe and C are useful in science.
Describe how evidence from a separation experiment could show whether a sample is a mixture.
Compare air, carbon dioxide and iron using the terms element, compound, mixture and particle.
Write a full explanation of how particle theory helps classify matter.
Part C
Research and understanding task
Research one everyday material, such as air, milk, steel, concrete, seawater or soft drink. Classify it as an element, compound or mixture and explain your evidence.