CAIE A Level Chemistry 9701 · Atomic structure
Oxygen has three naturally occurring isotopes, , and .
(a) Define the term isotope, in terms of protons and neutrons.
(b) Explain why isotopes of oxygen have the same chemical properties.
(c) A gas jar contains oxygen that is almost entirely and an identical jar contains oxygen that is almost entirely , at the same temperature and pressure. Explain, using the idea of density, why the first jar has the greater density.
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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