CAIE A Level Chemistry 9701 · Atomic structure
An atom of element Q has a proton number of 12 and a nucleon number of 24. The neutral atom forms a cation with a charge of 2+. Explain, in terms of the relative charges and relative masses of protons, neutrons and electrons, why the cation has a 2+ charge and why its mass is almost the same as that of the neutral atom.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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