Question

Which is more radioactive- an isotope with a long half-life or an isotope with a short half-life?

Short answer

An isotope with a short half-life is more radioactive.

Step-by-step solution

Understanding Half-Life

Half-life is the time it takes for half of the radioactive nuclei in a sample to decay. It is a measure of the rate at which a substance undergoes radioactive decay. The shorter the half-life, the faster the substance decays.

Comparing Decay Rates

An isotope with a short half-life decays more quickly, meaning it releases radiation at a faster rate than an isotope with a long half-life. Because radioactive isotopes emitting radiation more quickly are considered more radioactive, this indicates a stronger activity level.

Conclusion on Radioactivity

Therefore, an isotope with a short half-life is more radioactive because it has a higher decay rate, releasing more radiation in a given period.

Key concepts

Half-Life

Half-life is a fundamental concept in understanding radioactive isotopes. It refers to the time required for half of the nuclei in a radioactive sample to decay. Different isotopes have varying half-lives, ranging from a fraction of a second to millions of years. This variability in half-life helps scientists determine how quickly a given isotope will lose its radioactivity.
Think of half-life like a clock ticking down to half the amount of what was there before. For example, if you have 100 radioactive atoms and their half-life is 10 minutes, after 10 minutes, you'd have 50 radioactive atoms left. After another 10 minutes, just 25, and so on.
Understanding this concept is crucial for radioactivity applications, such as dating archaeological finds or determining the safety of nuclear materials.

Radioactive Decay

Radioactive decay is the process by which an unstable atomic nucleus loses energy. This loss of energy occurs in the form of emitted radiation, which can be particles (like alpha and beta particles) or electromagnetic waves (like gamma rays).
During this process, the nucleus of a radioactive isotope transforms into another element or a different isotope of the same element, which could be stable or continue to decay further. The rate of decay is probabilistic, meaning it isn't possible to predict the exact moment a particular atom will decay, only the likelihood that it will decay over a certain period.
Over time, as radioactive decay occurs and atoms change, the substance gradually loses its radioactivity. This principle forms the basis for numerous technologies and scientific studies, including understanding how old a sample is or how long a radioactive source will remain active.

Decay Rate

The decay rate represents how quickly an isotope undergoes radioactive decay. A key factor influencing the decay rate is the half-life of the radioactive substance. When an isotope has a short half-life, it decays rapidly, releasing its radiation in a brief timespan. Conversely, isotopes with long half-lives decay more slowly.
To visualize this, consider two different isotopes: one with a half-life of 1 day and another with a half-life of 1 year. The isotope with the 1-day half-life will emit radiation at a much faster pace than the 1-year isotope. This reveals a crucial aspect of radioactivity: the rate at which radiation is emitted.

• Isotopes with a high decay rate can be more harmful due to increased radiation exposure.
• Understanding decay rate aids in handling radioactive materials safely.

Isotope Comparison

When comparing isotopes to determine which is more radioactive, the decay rate becomes a pivotal factor. An isotope's level of radioactivity is often linked directly to how quickly it releases its radiation.
Isotopes with shorter half-lives decay at a faster rate, thus being more active in emitting radiation. This makes them more radioactive compared to isotopes with longer half-lives. Such comparisons help scientists select appropriate isotopes for different applications, like medical treatments or scientific research.
Choosing an isotope for a specific task involves understanding its half-life and the level of radioactivity it will offer. For long-term applications, isotopes with longer half-lives might be preferred. Conversely, for instantaneous results, those with shorter half-lives could be more suitable.