Question

What is a positron? What are the mass number and charge of a positron? How do the mass number and atomic number of a nucleus change when the nucleus produces a positron?

Short answer

A positron is a subatomic particle with the same mass as an electron but with a positive charge. Its mass number is 0, and its charge is +1. When a nucleus produces a positron through beta-plus decay, its mass number remains the same but its atomic number decreases by 1.

Step-by-step solution

Description of a positron

A positron, also known as a positive electron or antielectron, is a subatomic particle with the same mass as an electron but with a positive charge. It is the antiparticle of an electron and is involved in processes like beta-plus radioactive decay.

Mass number and charge of a positron

The mass number of a positron is the sum of its protons and neutrons. Since a positron has no protons or neutrons (it is a lepton, without strong nuclear force interactions), its mass number is 0. The charge of a positron is +1, which is equal in magnitude but opposite in sign to that of an electron.

Change in mass number and atomic number during positron production

When a nucleus produces a positron, it undergoes a process called beta-plus decay or positron emission. In this process, a proton within the nucleus is converted into a neutron, a positron, and a neutrino. The mass number (A) remains the same, as the total number of protons and neutrons in the nucleus does not change. However, the atomic number (Z) decreases by 1, as one proton is converted to a neutron, losing one positive charge. Let's summarize the information: 1. A positron is a subatomic particle with the same mass as an electron but with a positive charge. 2. The mass number of a positron is 0, and its charge is +1. 3. When a nucleus produces a positron through beta-plus decay, its mass number remains the same, but its atomic number decreases by 1.

Key concepts

Understanding Subatomic Particles

The world of the very small, such as subatomic particles, is both fascinating and complex. These fundamental components of matter make up the atoms that form everything around us. A subatomic particle is categorized based on its properties and interactions. Among them, there are three basic types: protons, neutrons, and electrons.Protons carry a positive charge, neutrons have no charge, and electrons are negatively charged. In contrast to protons and neutrons that form the nucleus of an atom, electrons orbit around the nucleus. The stability and reactions of atoms depend largely on these particles. However, there's more to the subatomic world than just these three particles - for instance, there are leptons, like the electron, and their antiparticles, such as the positron.

Deciphering Beta-Plus Decay

Beta-plus decay, also known as positron emission, is a type of radioactive decay, a natural process where an unstable nucleus transforms to become more stable. This occurs when a proton in the nucleus is converted into a neutron with the emission of a positron and a neutrino.

During this process, the proton, which is positively charged, disappears, and a neutron, which has no charge, takes its place while a positron, a particle with the same mass as an electron but with a positive charge, is emitted. It is important to note that the mass number of the atom does not change because the total number of protons and neutrons—the nucleons—remains constant. However, because one of these protons has changed into a neutron, the atomic number decreases by one.

Exploring Radioactive Decay

Radioactive decay is a fundamental natural phenomenon by which an unstable atomic nucleus loses energy by radiation. It comes in several forms, including alpha, beta, and gamma decay. Each type involves the emission of particles or energy from an atom's nucleus and can transform the element into another.

In beta-plus decay, not only a positron is emitted, but also a particle called a neutrino, which is incredibly light and rarely interacts with matter. Radioactive decay is a random process at the level of single atoms, meaning it is impossible to predict when a particular atom will decay. However, for a large number of atoms, the decay rate can be characterized by the half-life, which is the time taken for half of the radioactive atoms in a sample to decay.