CAIE A Level Chemistry 9701 · Atomic structure
Describe the ground-state electronic configurations of a chromium atom (Cr, atomic number 24) and the chromium(III) ion (Cr+). Explain why the chromium atom has the configuration [Ar] 3d^5 4s^1 rather than [Ar] 3d^4 4s^2, and explain why the configuration of Cr+ is [Ar] 3d^3.
7 marks, so the mark scheme is looking for about 7 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
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