Atoms, periodic table and reactions — Short response

Conceptual Understanding

Explain core models, definitions and relationships before using them in context.

In one or two sentences, explain why two different isotopes of the same element are still the same element, even though their mass numbers differ.
1 mark
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A neutral sodium atom is in Group 1. In the shell model, explain why sodium usually forms a 1+ ion rather than gaining enough electrons to fill its outer shell like a noble gas.
2 marks
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In two short sentences, explain why periodic table groups are useful for predicting chemical behaviour.
2 marks
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In one or two sentences, explain what a balanced chemical equation shows about atoms, and how that links to conservation of mass in a closed system.
2 marks
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Contrast ionic bonding and covalent bonding in two short sentences: say how electrons are involved in each case.
2 marks
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Use the same ideas to reason through scenarios, evidence, claims or investigations.

Copper metal is added to aqueous zinc sulfate. Using the idea of a metal activity series, predict whether a displacement reaction will occur and justify your prediction.
2 marks
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Heating a reaction mixture often makes it go faster. Explain why, using particle collisions and activation energy together, in about three sentences.
3 marks
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Magnesium ribbon is added to aqueous copper sulfate. Predict whether a displacement reaction occurs and justify your answer using the metal activity series.
2 marks
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A reaction involves gases mixed in a sealed syringe. Explain why compressing the mixture to a smaller volume can increase the reaction rate, using particle collisions.
2 marks
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A student says a fizzing reaction must be faster because it makes more product overall. Improve this claim by distinguishing reaction rate from amount of product.
2 marks
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