Question

Name two isotopes that have been used in radioactive dating.

Short answer

Carbon-14 and Uranium-238.

Step-by-step solution

Understand Isotopes in Radioactive Dating

Radioactive dating is a process that uses the decay rates of isotopes to determine the age of a material. Isotopes are versions of elements with the same number of protons but different numbers of neutrons.

Identify Common Isotopes for Dating

The most commonly used isotopes in radioactive dating include Carbon-14 and Uranium-238. Carbon-14 is used primarily for dating organic materials up to about 50,000 years old, while Uranium-238 is used for dating rocks and minerals over millions of years old.

Key concepts

Isotopes

Isotopes are like siblings in the family of elements, sharing some features while differing in others. Every isotope of a given element has the same number of protons, which means they belong to the same element on the periodic table. However, they differ in the number of neutrons, which leads to varying atomic masses.
This unique property of isotopes plays a crucial role in radioactive dating. Radioactive isotopes decay over time, changing into other elements or isotopes at a predictable rate. Scientists use this rate, known as the half-life, to measure how long ago an artifact or rock was formed. By examining the ratio of the original radioactive isotope to its decay products, we can calculate the age of the specimen.

• Each isotope's half-life is constant and unique.
• Researchers must choose the right isotope for the material and timeline they wish to explore.
• The decay rate provides a clock-like mechanism for dating materials.

Carbon-14

Carbon-14 is a superstar in the world of radioactive dating, especially when it comes to dating archaeological artifacts and fossils. It is an isotope of carbon and contains six protons and eight neutrons, differing from its more stable sibling, Carbon-12, which has six protons and six neutrons.
This isotope is particularly useful for dating once-living things, like plants and animals. While alive, organisms take in carbon, including Carbon-14, from their environment. Upon death, they stop absorbing carbon, and the Carbon-14 within them begins to decay at a known rate, with a half-life of approximately 5,730 years.

• Carbon-14 is suitable for dating materials that are up to about 50,000 years old.
• This isotope provides insights into ancient civilizations and historical timelines.
• Combining Carbon-14 dating with other methods can offer a more comprehensive view of an artifact's history.

Uranium-238

Uranium-238 is a heavyweight among radioactive isotopes, chiefly used in dating geological formations. Unlike Carbon-14, Uranium-238 is perfect for determining the age of rocks and minerals that are millions, if not billions, of years old. This isotope contains 92 protons and 146 neutrons.
One of the key aspects of Uranium-238 is its extremely long half-life, about 4.5 billion years. Because of this long half-life, it is an excellent tool for dating the Earth's oldest rocks as well as extraterrestrial objects, like meteorites. Over time, Uranium-238 decays through a series of steps into stable Lead-206, providing a timestamp for geological processes.

• Uranium-238 is invaluable in studying Earth's formation and the age of the solar system.
• It's ideal for dating inorganic materials, such as zircon crystals found in ancient rocks.
• The ability to date in such a broad timeframe provides crucial data for understanding the planet's history.