Problem 20 - Chemistry: Introducing Inorganic, Organic and Physical Chemistry

Question

Identify the transuranic element isotopes \(X, Y,\) and \(Z\) that were prepared by the following nuclear reactions. (Section 3.8 ) (a) \(^{241} \mathrm{Am}+^{4} \mathrm{He} \rightarrow \mathrm{X}+2^{1} \mathrm{n}\) (b) \(^{206} \mathrm{Pb}+^{64} \mathrm{Ni} \rightarrow \mathrm{Y}+^{1} \mathrm{n}\) (c) \(^{249} \mathrm{Cf}+^{18} \mathrm{O} \rightarrow \mathrm{Z}+4^{1} \mathrm{n}\)

Step-by-Step Solution

Answer

X is \(^{243} \mathrm{Bk}\), Y is \(^{269} \mathrm{Ds}\), Z is \(^{263} \mathrm{Sg}\).

Step 1: Identify Transuranic Elements

Transuranic elements are those with atomic numbers greater than 92, which means they are all elements following Uranium in the periodic table. In the given reactions, we are looking for elements that are products of these reactions and fit this description.

Step 2: Analyze Reaction (a)

Given: \[^{241} \mathrm{Am} + ^{4} \mathrm{He} \rightarrow \mathrm{X} + 2^{1} \mathrm{n}\]First, add the atomic numbers and mass of the reactants: Americium (Am) has an atomic number of 95, and Helium (He) has 2. This adds up to 97 for the product X.The mass number will be 241 (Am) + 4 (He) - 2 (neutrons) = 243.Element 97 is Berkelium (Bk), thus X is \(^{243} \mathrm{Bk}\).

Step 3: Analyze Reaction (b)

Given: \[^{206} \mathrm{Pb} + ^{64} \mathrm{Ni} \rightarrow \mathrm{Y} + ^{1} \mathrm{n}\]Add the atomic numbers: Lead (Pb) has 82, and Nickel (Ni) has 28.This gives an atomic number of 110.The mass number will be 206 (Pb) + 64 (Ni) - 1 (neutron) = 269.Element 110 is Darmstadtium (Ds), so Y is \(^{269} \mathrm{Ds}\).

Step 4: Analyze Reaction (c)

Given: \[^{249} \mathrm{Cf} + ^{18} \mathrm{O} \rightarrow \mathrm{Z} + 4^{1} \mathrm{n}\]Add the atomic numbers: Californium (Cf) is 98, and Oxygen (O) is 8, giving 106.The mass number will be 249 (Cf) + 18 (O) - 4 (neutrons) = 263.Element 106 is Seaborgium (Sg), meaning Z is \(^{263} \mathrm{Sg}\).

Key Concepts

Nuclear Reactions

Nuclear reactions involve the change in an atom's nucleus and are responsible for powering stars and some elements on Earth. The reactions result in the transformation of one element into another by changing the number of protons or neutrons in the nucleus. This can occur naturally or be induced in laboratory settings. In nuclear reactions, the total mass number and atomic numbers are conserved.
- **Types of Nuclear Reactions:** - **Fusion:** Light nuclei combine to form a heavier nucleus. It powers the sun. - **Fission:** A heavy nucleus splits into lighter nuclei, often releasing a significant amount of energy. Used in nuclear power plants. - **Transmutation:** A nucleus is transformed into another element by particles bombarding it, like neutrons or alpha particles.
- **Applications:** Nuclear reactions are crucial in medicine for imaging and cancer therapy, and in energy production and radioactive dating. They also facilitate the creation of new elements in laboratories, including transuranic elements like Berkelium, Darmstadtium, and Seaborgium.

Berkelium

Berkelium is a man-made transuranic element with the symbol Bk and atomic number 97. It was first synthesized in 1949 by bombarding Americium with alpha particles (Helium nuclei).
- **Characteristics:** - It is a radioactive element and part of the actinide series. - Berkelium does not occur naturally and must be produced in nuclear reactors.
- **Uses:** While Berkelium itself has no significant commercial applications, it is used in scientific research, particularly in producing other transuranic elements and isotopes. - **Handling:** Due to its radioactivity, it is handled with caution, requiring specialized facilities designed to contain radioactive isotopes.
Discovering and studying Berkelium helps scientists understand the properties of heavy elements and the forces holding atomic nuclei together.

Darmstadtium

Darmstadtium, with the symbol Ds and atomic number 110, is a synthetic element named after the city of Darmstadt in Germany, where it was discovered. This element belongs to the group of "super-heavy elements" and is produced in a particle accelerator. - **Properties:** - Darmstadtium is not found naturally and has a very short half-life. - It is a part of the transition metals in the periodic table. - Scientists suspect it to be a solid metal at room temperature based on its position in the periodic table. - **Synthesis:** It is created by bombarding a heavy element like Lead with a lighter element such as Nickel. - **Research Significance:** Although it has no practical uses due to its quick decay, studying Darmstadtium enables researchers to explore nuclear reactions and stability trends in the periodic table.

Seaborgium

Seaborgium, symbolized as Sg with an atomic number of 106, is another synthetic element discovered through nuclear reactions. Named in honor of the chemist Glenn T. Seaborg, this element exemplifies the exploration of super-heavy elements.
- **Formation:** Seaborgium is made by colliding atoms of Cf (Californium) with O (Oxygen) in a particle accelerator. - **Features:** - It belongs to the group 6 transition metals. - Like other transuranic elements, its isotopes have very short half-lives, making it challenging to work with. - **Scientific Interest:** Research on Seaborgium aids in understanding chemical behaviors of heavy elements, offering insights into structural and theoretical chemistry. - **Challenges:** Its rapid decay limits detailed study, requiring exceptionally swift experimental analysis. The pursuit to synthesize and study elements like Seaborgium underscores the ongoing effort to expand our understanding of the periodic elements and the strong nuclear forces involved.