Question

What do these symbols stand for? (a) \({ }_{0}^{0} \gamma,(\mathbf{b}){ }_{2}^{4} \mathrm{He},\) (c) \({ }_{0}^{1} \mathrm{n} .\)

Short answer

The notations represent the following particles: (a) \({ }_{0}^{0} \gamma\) represents a gamma photon, which is a high-energy electromagnetic radiation emitted during radioactive decay or nuclear reactions. (b) \({ }_{2}^{4} \mathrm{He}\) represents a helium-4 nucleus or alpha particle, which is composed of two protons and two neutrons. (c) \({ }_{0}^{1} \mathrm{n}\) represents a neutron, a neutral particle found in the nucleus of atoms alongside protons.

Step-by-step solution

Identifying particle (a)\({ }_{0}^{0} \gamma\)

In this notation, the bottom number (0) represents the atomic number (the number of protons), the top number (0) represents the mass number (the total number of protons and neutrons), and the symbol \(\gamma\) denotes the gamma particle. Since the atomic number and the mass number are both 0, this indicates that the particle is a gamma photon. Gamma photons are high-energy electromagnetic radiation emitted during radioactive decay, nuclear reactions, or other high-energy processes.

Identifying particle (b)\({ }_{2}^{4} \mathrm{He}\)

In this notation, the bottom number (2) represents the atomic number (number of protons), the top number (4) represents the mass number (total number of protons and neutrons), and the symbol He denotes the helium atom. Since the atomic number is 2 and the mass number is 4, this indicates that the particle is a helium-4 nucleus, also known as an alpha particle. Alpha particles are composed of two protons and two neutrons, and are often emitted during radioactive decay.

Identifying particle (c)\({ }_{0}^{1} \mathrm{n}\)

In this notation, the bottom number (0) represents the atomic number (number of protons), the top number (1) represents the mass number (total number of protons and neutrons), and the symbol n denotes the neutron particle. Since the atomic number is 0 and the mass number is 1, this indicates that the particle is a neutron. Neutrons are neutral particles that reside in the nucleus of atoms, along with protons.

Key concepts

Gamma Photons

Gamma photons are an important part of nuclear chemistry, acting as high-energy electromagnetic radiation. These powerful rays emanate from a variety of sources, including radioactive decay, nuclear reactions, and other high-energy events. Unlike particles that have mass, gamma photons have no mass and no charge. Instead, they are packets of energy or quanta. This energy attribute makes them extremely penetrating and capable of traveling vast distances through materials, often requiring dense substances like lead or thick concrete to absorb them efficiently.

Key characteristics of gamma photons:

• No mass or electric charge
• High-energy electromagnetic radiation
• Emitted in nuclear processes
• Capable of penetrating materials

While gamma photons themselves are not particles in the traditional sense, their energy can have significant effects on matter, notably in medical treatments like cancer radiotherapy and in gamma-ray astronomy to study the universe.

Alpha Particles

Alpha particles are a type of ionizing radiation consisting of two protons and two neutrons bound together. Represented by \({ }_{2}^{4} \mathrm{He}\), they have an atomic number of 2 and a mass number of 4. This configuration makes them identical to the nucleus of a helium atom. Unlike gamma photons, alpha particles are indeed massive and positively charged due to the presence of protons.

Alpha particles are commonly produced in a process known as alpha decay, in which an unstable nucleus releases an alpha particle to become more stable. Due to their relatively large mass and charge, alpha particles have low penetration power and can be stopped by a sheet of paper or even the skin. However, they are very effective at transferring energy to the materials they pass through, which can make them hazardous if ingested or inhaled.

Essential properties of alpha particles:

• Consist of two protons and two neutrons
• Positively charged
• Low penetration ability
• Emitted during radioactive decay

In scenarios involving radiation protection, alpha particles demand certain precautions to prevent them from entering the body through breathing or ingestion.

Neutrons

Neutrons are fundamental subatomic particles with no electrical charge, found within the nucleus of an atom. As depicted by the symbol \({ }_{0}^{1} \mathrm{n}\), a neutron has a mass number of 1 and an atomic number of 0. This indicates their neutrality and is part of what makes them a unique component of nuclear reactions and nuclear structure.

Neutrons play a critical role in the stability of atomic nuclei. They help to bind protons within the nucleus by offsetting the repulsive forces due to the positive charge of protons. Additionally, neutrons are instrumental in nuclear fission processes, where they can initiate and propagate chain reactions. Given their lack of charge, neutrons can penetrate deeper into materials than charged particles, allowing them to be used in applications such as imaging and probing the properties of materials.

Notable features of neutrons include:

• Neutral charge
• Located in the nucleus alongside protons
• Essential for nuclear stability
• Involved in fission and neutron-based applications

Understanding the behavior of neutrons is indispensable for fields such as nuclear energy and material science.