 Solution

ID: past-exam-of-the-chemistry-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2025/2/a/ii/solution

The lowest two energy levels have $n = 1$ and $n = 2$ . For carbon,

Z = 6

, even though the ion's net charge is

5 +

E_{1} = - 36 (2.180 \times 1 0^{- 18}) = - 7.848 \times 1 0^{- 17} J, E_{2} = \frac{E _{1}}{4} = - 1.962 \times 1 0^{- 17} J .

Increasing

n

raises the energy toward zero; the most negative value is the ground-state energy.

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