Question

Production of a helium nucleus from a heavy atom is referred to as decay.

Short answer

The production of a helium nucleus from a heavy atom is referred to as alpha decay. This type of radioactive decay involves the emission of an alpha particle (or helium nucleus with 2 protons and 2 neutrons) and transforms the parent atom into a new element with a lower atomic number. The alpha decay process can be represented as \( ^A_ZX \rightarrow ^{A-4}_{Z-2}Y + ^4_2\alpha \), with conservation of mass and charge. The released energy (Q-value) is carried by the emitted alpha particle in the form of kinetic energy.

Step-by-step solution

Understanding Decay

Decay is a spontaneous process in which an unstable atomic nucleus loses energy by emitting particles (such as alpha particles, beta particles, or gamma rays) or radiation. In this case, we are focusing on the production of a helium nucleus, which occurs during alpha decay.

Describe Alpha Decay

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle (consisting of 2 protons and 2 neutrons) and transforms into a new element with a lower atomic number. The alpha particle produced is essentially a helium nucleus.

Illustrate the Alpha Decay Equation

Consider a heavy atom with atomic number Z and mass number A. During alpha decay, the atom loses 2 protons and 2 neutrons, forming a helium nucleus. The alpha decay can be represented by the following equation: \( ^A_ZX \rightarrow ^{A-4}_{Z-2}Y + ^4_2\alpha \) Where: - \( ^A_ZX \) represents the initial atom with atomic number Z and mass number A - \( ^{A-4}_{Z-2}Y \) represents the resulting atom after alpha decay, with atomic number (Z-2) and mass number (A-4) - \( ^4_2\alpha \) is the emitted alpha particle or helium nucleus

Conservation Laws in Alpha Decay

During alpha decay, both mass and charge are conserved. The conservation of mass means that the mass number of the parent atom (A) must equal the combined mass numbers of the daughter atom and the helium nucleus. The conservation of charge means that the atomic number of the parent atom (Z) must equal the combined atomic numbers of the daughter atom and the helium nucleus.

Energy Release During Alpha Decay

Since this decay process is spontaneous, the parent atom loses energy during alpha decay. The energy released can be calculated using the difference in the masses of the parent atom and the sum of the masses of the daughter atom and the helium nucleus. This released energy, known as the Q-value, is carried away by the emitted alpha particle in the form of kinetic energy.

Key concepts

Radioactive Decay

Radioactive decay is a natural process where unstable atomic nuclei lose energy to attain stability. This can occur through the emission of particles like alpha, beta, and gamma rays.
A primary example is alpha decay, in which an unstable nucleus emits an alpha particle. This process lowers its energy and transforms it into a different element.

• Alpha particles consist of two protons and two neutrons, similar to a helium nucleus.
• The nucleus of the atom changes, reducing its atomic number and mass.

Such transformations allow the nucleus to reach a more stable state, removing excess energy and shifting its identity based on the transformed element. Understanding decay helps us examine natural and artificial nuclear processes.

Helium Nucleus

A helium nucleus, also known as an alpha particle, is a small cluster of two protons and two neutrons. It is positive in charge, thanks to its protons.
When a heavy nucleus undergoes alpha decay, it ejects this alpha particle, which contributes to the change in the original element's structure.

• Helium nucleus creation marks not just a shift in atomic structure but also mass loss.
• It is incredibly stable, explaining why alpha particles are chosen by nature as emission candidates in radioactive decay.
• After emission, it travels away, carrying energy as kinetic energy.

This behavior of the helium nucleus not only alters the initial atom but also helps the universe in maintaining atomic stability.

Conservation Laws

Conservation laws are crucial in understanding alpha decay. These laws ensure that certain physical quantities remain consistent before and after a reaction.
During alpha decay, both mass and charge need to be conserved.

• The conservation of mass states that the mass number of the parent atom equals the total mass number of the daughter atom and the helium nucleus. This is why we see a reduction in mass number by four in alpha decay equations.
• The conservation of charge requires the atomic number of the parent atom to match the total atomic number of the daughter and helium nucleus. In practice, this results in a reduction by two of the atomic number.

These laws are key to understanding the equation represented as:
\(^A_ZX \rightarrow ^{A-4}_{Z-2}Y + ^4_2\alpha\)

They provide us with a robust framework to predict the products of alpha decay and validate the principles of physics in nuclear reactions.