21. Nuclear Chemistry

Indicate whether each of the following nuclides lies within the belt of stability in Figure 21.2: (a) neon-24. For any that do not, describe a nuclear decay process that would alter the neutron-to-proton ratio in the direction of increased stability. [Section 21.2]

Despite the similarities in the chemical reactivity of elements in the lanthanide series, their abundances in Earth's crust vary by two orders of magnitude. This graph shows the relative abundance as a function of atomic number. Which of the following statements best explains the sawtooth variation across the series? (a) The elements with an odd atomic number lie above the belt of stability. (b) The elements with an odd atomic number lie below the belt of stability. (c) The elements with an even atomic number have a magic number of protons. (d) Pairs of protons have a special stability.

The first six elements of the first transition series have the following number of stable isotopes: Element Number of Stable Isotopes Sc 1 Ti 5 V 1 Cr 3 Mn 1 Fe 4 Explain why Sc, V, and Mn each have only one stable isotope while the other elements have several.

Predict a likely mode of decay for each unstable nuclide. a. Mo-109

(c) What other substances are used as a moderator in nuclear reactor designs?

In 2010, a team of scientists from Russia and the United States reported creation of the first atom of element 117, which is named tennessine, and whose symbol is Ts. The synthesis involved the collision of a target of 24997Bk with accelerated ions of an isotope which we will denote Q. The product atom, which we will call Z, immediately releases neutrons and forms 294117Ts: 24997Bk + Q¡Z¡294117Ts + 3 10n (b) Isotope Q is unusual in that it is very long-lived (its half-life is on the order of 1019 yr) in spite of having an unfavorable neutron-to-proton ratio (Figure 21.1). Can you propose a reason for its unusual stability?