Question

Which type of particle is emitted in the nuclear decay reaction shown here? \({ }_{88}^{222} \mathrm{Ra} \rightarrow{ }_{86}^{218} \mathrm{Rn}+{ }_2^4 \mathrm{He}\) (A) alpha decay (B) beta decay (C) gamma decay (D) nuclear fusion

Short answer

The emitted particle in the given nuclear decay reaction is an alpha particle, as indicated by the presence of \({ }_2^4 \mathrm{He}\) in the products. Therefore, the correct answer is (A) alpha decay.

Step-by-step solution

Identify the reactants and products in the nuclear decay reaction

For the given nuclear decay reaction, we have the following reactants and products: Reactants: \({ }_{88}^{222} \mathrm{Ra}\) Products: \({ }_{86}^{218} \mathrm{Rn}\) and \({ }_2^4 \mathrm{He}\)

Determine the emitted particle

In this decay reaction, Radium (\({}_{88}^{222} \mathrm{Ra}\)) transforms into Radon (\({}_{86}^{218} \mathrm{Rn}\)) and a particle with \({ }_2^4 \mathrm{He}\) notation, which represents a Helium nucleus with atomic number 2 and atomic mass 4. The Helium nucleus (\({ }_2^4 \mathrm{He}\)) consists of 2 protons and 2 neutrons. This particle is called an alpha particle.

Choose the correct type of particle emission

Since the emitted particle in this nuclear decay reaction is an alpha particle, the correct answer is: (A) alpha decay

Key concepts

Alpha Decay

Alpha decay is a type of radioactive decay where an unstable atomic nucleus releases an alpha particle. An alpha particle consists of 2 protons and 2 neutrons, which is essentially a helium nucleus (denoted \(_2^4 \mathrm{He}\)). When alpha decay occurs:

• The atomic number decreases by 2.
• The atomic mass reduces by 4 units.

This process results in the creation of a new element. In the example provided, the element Radium \(_{88}^{222} \mathrm{Ra}\) undergoes alpha decay to form Radon \(_{86}^{218} \mathrm{Rn}\). Consequently, our understanding of alpha decay plays a crucial role in fields such as nuclear physics and radiometric dating.

Radioactive Particles

Radioactive particles are tiny fragments emitted from a nucleus during radioactive decay. These particles include:

• Alpha particles: Consist of 2 protons and 2 neutrons. They are large and heavy compared to other particles.
• Beta particles: Essentially high-speed electrons or positrons that are ejected from the nucleus of an atom.
• Gamma rays: High-energy electromagnetic waves emitted from a nuclear transition.

These particles interact differently with matter. Alpha particles, for example, have a high ionization power due to their size but are not very penetrating. They can be stopped by a sheet of paper or human skin. Understanding the properties of these particles helps in applications ranging from nuclear medicine to energy production.

Nuclear Reactions

Nuclear reactions describe transformations involving changes in an atom's nucleus. In radioactive decay, a common type of nuclear reaction, unstable atoms spontaneously transform to become stable, releasing energy in the process. Key characteristics of nuclear reactions include:

• Involvement of the nucleus rather than the entire atom.
• Emission of particles like alpha or beta particles.
• Release of large amounts of energy compared to chemical reactions.

Nuclear reactions can be further categorized into processes like fission, fusion, and radioactive decay. Alpha decay, for instance, is a specific kind of radioactive decay. These reactions have substantial implications in areas such as nuclear energy, where the same principles apply in reactors that produce electricity by splitting nuclei in a controlled manner.