CAIE A Level Chemistry 9701 · Chemical bonding
A student claims that a dot-and-cross diagram of methane, , shows that in any molecule every atom must have eight electrons in its outer shell. Suggest how you would use dot-and-cross diagrams of methane, , phosphorus(V) chloride, , and nitrogen dioxide, , to show that this claim is incorrect.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Suggest means: Apply what you know to an unfamiliar situation. There may be more than one acceptable answer. Reason from the principle you have learned to the new context, and say which principle you are using.
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