Compounds of the alkali metals
1 mark · EasyState what you would see when a piece of freshly cut lithium is left exposed to air.
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The surface of lithium tarnishes (becomes dull) slowly.
Also accept: Shiny surface becomes dull slowly.; It forms a dull coating.; It loses its shine slowly when left in air.
Common mistakes: Saying it reacts very quickly (which is faster for potassium/sodium).
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Marking points
B1 · 1 mark · States that lithium tarnishes slowly or forms a dull coating when left in air.
Worked solution
When a piece of freshly cut lithium is left exposed to air, its shiny surface slowly becomes dull as it reacts with oxygen to form a coating of lithium oxide.