Question

Describe the process of radioactive decay. Use the terms isotope, nucleus, and half-life in your answer.

Short answer

Radioactive decay is the process where unstable nuclei lose energy, changing an isotope over time, and is measured by half-life.

Step-by-step solution

Understanding Radioactive Decay

Radioactive decay is a natural process where an unstable atomic nucleus loses energy by emitting radiation. Over time, this leads to the transformation of the original nucleus into a different element or a different isotope of the same element.

Defining an Isotope

An isotope is a variant of a particular chemical element that shares the same number of protons in the nucleus but has a different number of neutrons. This difference in neutron count can make an isotope unstable, causing it to undergo radioactive decay.

Role of the Nucleus

The nucleus, which consists of protons and neutrons, is the region where radioactive decay occurs. When the nucleus is unstable due to an excess or deficiency of neutrons, it may release particles or energy in an attempt to reach a more stable state.

Understanding Half-life

Half-life is the time required for half of a sample of a radioactive isotope to decay. It is a measure of the rate of decay and varies widely between different isotopes, ranging from fractions of a second to millions of years.

Applying Concepts

In radioactive decay, an isotope such as Carbon-14 (an unstable form) will decay over time. Using its known half-life, scientists can predict how long it will take for a certain portion of the isotope to decay into a more stable form, such as Nitrogen-14.

Key concepts

Isotope

An isotope is like a member of a family where each member shares some common characteristics but has its own unique features. In chemistry, isotopes belong to the same chemical element. However, they differ in the number of neutrons found in their nucleus, while possessing the same number of protons. This variation leads to different mass numbers for isotopes of the same element.

Isotopes play a crucial role in radioactive decay. When an isotope has an imbalance in the number of neutrons, it may become unstable. This instability can lead to the isotope undergoing radioactive decay—where it transforms into a more stable state. Often, this results in the isotope turning into another element or another isotope of the original element.

For instance, isotopes of carbon include Carbon-12, Carbon-13, and the radioactive Carbon-14. While Carbon-12 and Carbon-13 are stable, Carbon-14 is radioactive and decays over time, forming nitrogen.

Nucleus

The nucleus is the heart of an atom, containing both protons and neutrons. Protons possess a positive charge, while neutrons are neutral. Together, they constitute nearly the entire mass of an atom. The nucleus is incredibly dense and compact.

In the context of radioactive decay, the nucleus is where the action happens. It may not always remain stable, especially if there is an abnormal ratio of neutrons to protons. An unstable nucleus will seek to return to a stable state by releasing particles, such as alpha or beta particles, or by emitting energy, such as gamma radiation. This transformation process often results in a completely new nucleus, potentially changing the element itself.

• Alpha decay results in the emission of helium nuclei.
• Beta decay involves the conversion of a neutron into a proton or vice versa.
• Gamma decay is the emission of energy without a change in the number of protons or neutrons.

This constant search for stability drives the phenomenon of radioactive decay.

Half-life

Half-life is a pivotal concept in understanding the timing and rate of radioactive decay. It describes the duration required for half of a radioactive isotope's nuclei to decay into a different form.

Each radioactive isotope has a distinctive half-life, ranging from microseconds to millions of years. This predictable rate of decay allows scientists to measure time periods in various applications, such as dating archaeological finds or gauging the age of geological formations. For example, the half-life of Carbon-14, which is used in radiocarbon dating, is about 5730 years.

The idea of half-life is essential because it enables the prediction of how a radioactive substance's activity decreases over time. Even though we cannot predict exactly when a single atom will decay, half-life gives us a statistical glimpse into how long large amounts of isotopes will last. It therefore serves as a clock within radioactive materials, helping us to understand and anticipate changes in a material's composition over time.