Question

What nuclide undergoes nuclear fission to give barium-143, krypton-88, and three neutrons?

Short answer

The parent nuclide is uranium-235.

Step-by-step solution

Understand the Problem

We need to determine the original nuclide (parent nucleus) that undergoes nuclear fission to produce barium-143, krypton-88, and three neutrons.

Write the Nuclear Fission Equation

The nuclear fission reaction can be written as follows:\[\text{Parent Nucleus} \rightarrow \text{Barium-143} + \text{Krypton-88} + 3 \text{ Neutrons} \] We need to find the parent nucleus on the left-hand side of this equation.

Determine the Atomic Mass Number

The atomic masses of the products are:- Barium-143 (A = 143)- Krypton-88 (\(A = 88\))- Neutrons (3 \(A = 1\) each)So, the combined atomic mass number of the products is:\[143 + 88 + 3 \times 1 = 234\]The parent nucleus must have an atomic mass number of 234.

Determine the Atomic Number

The atomic numbers of the products are:- Barium-143 (\(Z = 56\))- Krypton-88 (\(Z = 36\))- Neutrons (\(Z = 0\))So, the combined atomic number of the products is:\[56 + 36 + 0 = 92\]The parent nucleus must have an atomic number of 92.

Identify the Parent Nuclide

A nucleus with an atomic number of 92 corresponds to uranium. Thus, we conclude the parent nuclide undergoing fission is uranium-235 (\(_{92}^{235}\text{U}\)), as it fits both the atomic number and mass number requirements.

Key concepts

Parent Nucleus

In nuclear fission, the **parent nucleus** is the atom that undergoes a splitting process to produce smaller nuclei, known as fission products. It is essentially the starting point in a nuclear reaction where a heavy nucleus splits into lighter nuclei. This transformation results in a significant release of energy due to the conversion of mass into energy, as described by Einstein's famous equation \(E=mc^2\). To understand the role of the parent nucleus, consider that it must contain a specific arrangement of protons and neutrons that makes it capable of undergoing fission. The parent nucleus, like uranium-235, is chosen for its ability to spontaneously split when impacted by a neutron. The process is similar to triggering a chain reaction, where one nuclear event causes subsequent reactions. Characteristics to note about the parent nucleus:

• It is typically a large, unstable nucleus that can easily undergo spontaneous or induced fission.
• The identity of the parent nucleus is essential for determining the types and ratios of the fission products produced.
• A known example of a parent nucleus in fission reactions is uranium-235, widely used in nuclear reactors.

Understanding the role of the parent nucleus is crucial to grasping how nuclear fission chains reactions work and subsequently, how nuclear power plants generate energy.

Atomic Mass Number

The **atomic mass number** is an essential element when studying nuclear fission. It represents the total number of protons and neutrons in an atomic nucleus. Thus, it gives a measure of the mass of an atom.In the context of nuclear fission, knowing the atomic mass number is necessary for balancing a nuclear equation. In the given exercise, the total atomic mass number before and after the reaction provides insight into the identity of the parent nucleus. For instance, when uranium-235 undergoes fission, its atomic mass number helps determine the products formed and how they combine.Points to remember about the atomic mass number:

• It is represented by the symbol \(A\).
• It remains conserved in nuclear reactions, meaning the sum of the atomic mass numbers of the fission products equals that of the parent nucleus.
• In practical terms, knowing the atomic mass number helps identify unknown substances in nuclear reactions by calculations involving the masses of the products.

Comprehending the concept of atomic mass number aids in establishing the balance and understanding the details of fission in nuclear chemistry.

Atomic Number

The **atomic number** represents the number of protons in an atomic nucleus. It is a fundamental property that defines the identity of an element, indicating how it behaves chemically and physically. In terms of nuclear fission, the atomic number plays a critical role. It helps in identifying the parent nucleus by understanding the total number of protons involved before and after the reaction. For the exercise in question, knowing that the atomic number of uranium is 92 helps confirm its status as the parent nucleus, since post-fission, the sum of the atomic numbers of the fission products equals that of uranium-235.Important aspects about atomic number include:

• Denoted by the symbol \(Z\), it provides a unique identifier for each element on the periodic table.
• In nuclear reactions, the atomic number must balance out across both sides of the equation, just like the atomic mass number.
• This concept is crucial for discerning element identities in various nuclear transformations, including fission processes.

Understanding atomic numbers is vital for grasping how nuclear reactions capture and transform energy, providing a basis for deeper explorations into scientific and industrial applications of nuclear fission.