Question

What does the process of radioactive decay entail?

Short answer

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation, transforming the nucleus into a different element or a lower energy state, called a daughter isotope. There are several types of decay, including alpha decay, beta-minus decay, beta-plus decay, and gamma decay. For example, in alpha decay, an unstable nucleus emits an alpha particle (2 protons and 2 neutrons) and transforms into a different element with decreased mass and atomic numbers. In general, radioactive decay occurs when a nucleus seeks to become more stable by releasing particles or energy in the form of radiation.

Step-by-step solution

Define radioactive decay

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. This process transforms the nucleus into a different element or a lower energy state. The resulting atom is called a daughter isotope.

Explain different types of radioactive decay

There are several types of radioactive decay processes, including: 1. Alpha decay: The nucleus releases an alpha particle (a helium-4 nucleus consisting of two protons and two neutrons), transforming the atom into a different element with a mass number 4 less and atomic number 2 less than the original atom. 2. Beta-minus decay: A neutron in the nucleus is converted into a proton, and an electron (called a beta particle) is emitted. The resulting atom has an increased atomic number by 1. 3. Beta-plus decay: A proton in the nucleus is converted into a neutron, and a positron (the electron's antiparticle) is emitted. The resulting atom has a decreased atomic number by 1. 4. Gamma decay: The nucleus loses energy by emitting a high-energy photon in the form of gamma radiation. This process doesn't change the number of protons or neutrons in the nucleus but often results in a more stable energy state.

Describe the process of radioactive decay with an example

Let's examine the process of alpha decay as an example: 1. An unstable nucleus, such as uranium-238 (with 92 protons and 146 neutrons) reaches a point where it can no longer contain the internal forces. 2. To become more stable, the nucleus emits an alpha particle, which consists of 2 protons and 2 neutrons. 3. The remaining nucleus has 90 protons and 144 neutrons, forming a thorium-234 atom. 4. In this process, the original atom (uranium-238) decays to a more stable atom (thorium-234) by releasing an alpha particle. By understanding this example, one can apply the general concept to other types of radioactive decay, where the nucleus seeks to become more stable by emitting particles or energy in the form of radiation.

Key concepts

Alpha Decay

Alpha decay is a fascinating process where the nucleus of an unstable atom releases an alpha particle to become more stable. An alpha particle consists of two protons and two neutrons. When an atom undergoes alpha decay, its mass number decreases by 4 and its atomic number decreases by 2. For instance, if uranium-238 undergoes alpha decay, it releases an alpha particle and transforms into thorium-234. This change happens because two protons and two neutrons have been ejected, making the nucleus more stable and less massive. Alpha particles are positively charged and can be stopped by something as thin as a piece of paper. This makes them less penetrating compared to other types of radiation, but they can still pose health risks if inhaled or ingested.

Beta Decay

Beta decay comes in two flavors: beta-minus and beta-plus decay, and each has its unique characteristics. In beta-minus decay, a neutron converts into a proton, and an electron (beta particle) is released from the nucleus. This increases the atomic number by 1, changing the element. For example, carbon-14 changes into nitrogen-14. On the other hand, beta-plus decay involves a proton changing into a neutron and releasing a positron (the electron's antiparticle), decreasing the atomic number by 1. An example is the transformation of potassium-40 into argon-40. What's intriguing about beta decay is how it alters the identity of an element, making it a crucial process in the natural transmutation of elements in the universe.
Beta particles have a greater penetrative ability than alpha particles but can often be stopped by materials like plastic or glass.

Gamma Decay

Gamma decay is a bit unique compared to alpha and beta decay. It doesn't involve changing the number of protons or neutrons; instead, it deals with the energy state of the nucleus. During gamma decay, the unstable nucleus releases energy in the form of a gamma photon, which doesn't alter the nucleus's composition but moves it to a more stable energy level. This is similar to how an excited atom sheds excess energy. Gamma rays are highly penetrating and require dense materials like lead or concrete for shielding.
This type of decay typically follows alpha or beta decay when the daughter nucleus formed is in an excited state and needs to release energy to reach stability. Understanding gamma decay helps grasp the complexities of atomic stability and energy emissions.

Daughter Isotope

When an atom undergoes radioactive decay, the resulting atom is called a daughter isotope. This term refers to the new element or isotope formed after the parent nucleus undergoes decay. For example, when uranium-238 decays via alpha emission to form thorium-234, thorium-234 is the daughter isotope. The transformation preserves the law of conservation of mass and charge, which are integral in maintaining atomic balance. Identifying daughter isotopes is crucial in fields like geochronology, where they help determine the age of rocks and archaeological findings.
The study of daughter isotopes also facilitates the understanding of nuclear processes and radioisotopes, making it key in both scientific research and practical applications.