Question

What is carbon dating?

Hint:

Remember that carbon dating is only applicable to materials that were once alive (organic). It cannot be used to date rocks or metals. The key is the exchange of carbon with the environment, which stops at death.

Answer 1

Step 1: Understanding the Concept:
Carbon dating, also known as radiocarbon dating, is a scientific technique that uses the properties of a naturally occurring radioactive isotope of carbon (\(^{14}\)C) to determine the age of carbon-based materials up to about 50,000 to 60,000 years old.
Step 2: Detailed Explanation:
The principle behind carbon dating is as follows:
1. Formation of Carbon-14:
Cosmic rays from space strike the Earth's upper atmosphere, producing neutrons. These neutrons collide with Nitrogen-14 (\(^{14}\)N) atoms, converting them into Carbon-14 (\(^{14}\)C), which is radioactive.
\[ n + ^{14}\text{N} \rightarrow ^{14}\text{C} + p \] 2. Incorporation into Living Organisms:
This radioactive \(^{14}\)C combines with oxygen to form carbon dioxide (\(^{14}\text{CO}_2\)). This radioactive carbon dioxide mixes with regular carbon dioxide in the atmosphere and is absorbed by plants during photosynthesis. Animals then eat these plants. As a result, all living organisms continuously incorporate both stable carbon (\(^{12}\)C) and radioactive carbon (\(^{14}\)C) into their bodies, maintaining a relatively constant ratio of \(^{14}\)C to \(^{12}\)C, the same as in the atmosphere.
3. Decay After Death:
When an organism dies, it stops taking in carbon from the environment. The stable \(^{12}\)C in its tissues remains, but the radioactive \(^{14}\)C begins to decay back into Nitrogen-14 (\(^{14}\)N) with a known half-life of approximately 5,730 years.
\[ ^{14}\text{C} \rightarrow ^{14}\text{N} + e^- + \bar{\nu}_e \] 4. Age Determination:
By measuring the ratio of the remaining \(^{14}\)C to the stable \(^{12}\)C in a sample of organic material (like wood, bone, or cloth) and comparing it to the atmospheric ratio, scientists can calculate how many half-lives have passed since the organism died. This allows them to determine the age of the sample.
Step 3: Final Answer:
Carbon dating is a method of age determination for organic artifacts by measuring the decay of the radioactive isotope \(^{14}\)C they contain since the time of their death.