Question 43.2: Carbon and Nitrogen The most abundant isotope of carbon is C......
Carbon and Nitrogen
The most abundant isotope of carbon is Carbon-12, which has six protons and six neutrons, and the most abundant isotope of nitrogen is Nitrogen-14. However, for this problem consider Nitrogen-12, which has seven protons and five neutrons. Fill in energy-level diagrams (Fig. 43.4) for both nuclei. In the CHECK and THINK step, answer the question: Which nucleus has more energy?
INTERPRET and ANTICIPATE
Start at the lowest energy level and fill in protons and neutrons, while following Pauli’s exclusion principle.
SOLVE
Start with carbon. The six neutrons fill three boxes (spin up and spin down in each box), and likewise for the six protons (Fig. 43.6).
Follow the same procedure for nitrogen (Fig. 43.7).
CHECK and THINK
Because the last proton in nitrogen is in the fourth box, nitrogen has more energy than carbon, whose highest energy nucleons are only in the third box. However, this isotope of nitrogen is unstable, so one of its protons will transform into a neutron through a process known as inverse beta decay (Section 43-5).
