22-3-half-life-and-radiometric-dating_summary

This section is about the concept of half-life and its application in radiometric dating. Half-life is a term used to describe the time it takes for half of a sample of a radioactive isotope to decay. In this context, it shows the rate at which a radioactive substance decays. The concepts of half-life and radioactive decay are essential in the science of radiometric dating. This method is used to determine the age of organic and inorganic materials, such as rocks, fossils, and artifacts. The most common type of radiometric dating is carbon-14 dating, where carbon-14 isotopes that are part of living organisms decay over time. Once an organism dies, carbon exchange with the environment ends, and the decrease in carbon-14 can be used to determine the age of the artifact or sample. The problems associated with radiometric dating are solved by calculating half-life, decay constant, and activity of a radioactive isotope. These calculations can help determine the age of a sample. The SI unit for activity is one decay per second, known as the becquerel (Bq), while the curie (Ci) is a more common unit, defined as the activity of 1 g of 226Ra. A simple worked example demonstrates how to find the decay constant, find the amount of material remaining after a certain time, and calculate the activity of a radioactive isotope given its half-life. Another worked example shows how to calculate the age of the Shroud of Turin using the data obtained from carbon-14 dating. The Shroud of Turin, a famous relic, was recently carbon-14 dated and found to be consistent with its first record of existence, but not with the period in which Jesus lived. Other non-carbon forms of radioactive dating exist as well. For example, rocks can sometimes be dated based on the decay of uranium and thorium isotopes, which end with lead isotopes. The ratio of these nuclides in a rock can be used to indicate the age of the rock. Knowledge of half-life has shown that the oldest rocks on Earth solidified about 4.6 billion years ago. Lastly, it is mentioned that students should understand the concept of half-life in the context of other exponential decay phenomena such as atmospheric pressure and temperature difference between objects. The given section learning objectives help students master their understanding of the nature of forces in the physical world and simple examples of atomic, nuclear, and quantum phenomena.