Extracting metals from their ores
3 marks · NormalExplain, using the reactivity series, why gold can be found as a pure metal in the Earth's crust but magnesium cannot.
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Gold is very unreactive and does not combine easily with other elements, so it can be found native (pure) in the Earth's crust. Magnesium is much more reactive and always forms compounds, so it is never found as a free element in nature.
Must show: Gold is unreactive – found as element, Magnesium is reactive – only found combined
Also accept: Gold is less reactive than magnesium; Magnesium forms compounds with other elements
Common mistakes: Saying both can be found as elements; Not relating answer to reactivity
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Marking points
M1 · 1 mark · States that gold is unreactive (or very low in the reactivity series).
M1 · 1 mark · States that gold is found native/pure in Earth's crust.
M1 · 1 mark · States that magnesium is reactive and only found as compounds, not as pure element.
Worked solution
Gold is very unreactive, so it is found in the Earth's crust as a pure metal (native). Magnesium is much more reactive, so it always forms compounds and is not found as the free element.