Question

Which isotope is useful for dating wood and charcoal that is less than about 75,000 years old? A. carbon- 14 C. uranium-238 B. potassium \(-40\) D. argon-40

Short answer

Carbon-14 is the isotope used for dating wood and charcoal up to 75,000 years old.

Step-by-step solution

Understanding the Problem

The problem asks which isotope is suitable for dating wood and charcoal that are less than 75,000 years old. This means we need to identify an isotope with a half-life suitable for this time range.

Explore Isotope Properties

We need to look into the known isotopes: carbon-14, uranium-238, potassium-40, and argon-40, focusing on their half-lives and what materials they can date. Carbon-14 has a half-life of about 5,730 years, suitable for dating materials up to around 50,000 to 75,000 years old.

Fitting Isotope to the Time Range

Carbon-14 is used for dating relatively recent organic materials such as wood and charcoal because it is absorbed during their life cycle and its half-life aligns nicely with the age of the samples under consideration.

Conclusion

Since carbon-14 is effective in dating organic materials that are up to around 75,000 years old, and considering the materials in question are wood and charcoal, carbon-14 is the most suitable isotope for this context.

Key concepts

carbon-14

Carbon-14 is a radioactive isotope of carbon, which means it has an unstable nucleus that emits radiation as it decays. This particular isotope is crucial for carbon dating, a method used to determine the age of organic materials. Carbon-14 is naturally found in the environment and is absorbed by living organisms. When the organism dies, it stops taking in new carbon-14, and the existing carbon-14 within the organism starts to decay. This decay process is what makes carbon-14 an effective tool for dating, as scientists can measure the amount of carbon-14 remaining and estimate how long it has been since the organism's death.

Key reasons carbon-14 is used for dating include:

• It is naturally incorporated into living organisms.
• It has a half-life that aligns well with the time frames often encountered in archaeology and geology.
• It provides a means for estimating the dates of artifacts and remains up to approximately 75,000 years old.

isotope half-life

The half-life of an isotope is the time it takes for half of the radioactive atoms in a sample to decay. For carbon-14, the half-life is around 5,730 years. This means that over 5,730 years, half of an initial quantity of carbon-14 will have decayed into nitrogen-14. Understanding the half-life is crucial in radiocarbon dating because it provides the time scale over which the decay process can be measured and quantified effectively.

In practical terms, the half-life determines the range of ages that carbon dating can accurately estimate. Since carbon-14 has such a relatively short half-life compared to other isotopes used in dating, it is perfect for dating recent organic material. For example, if a wooden tool is found, scientists can determine how many half-lives have passed and subsequently calculate its age, assuming no contamination has occurred.

dating organic materials

Dating organic materials involves estimating the age of once-living objects, such as wood, charcoal, and bone. This is typically achieved through radiocarbon dating, which leverages the decay of carbon-14. Since all living organisms contain carbon, they will all contain carbon-14, which begins to decay at a known rate after the organism's death.

The process of dating involves:

• Collecting a sample of the organic material.
• Measuring the remaining carbon-14 levels.
• Comparing the measured levels to the initial levels typically found in similar living tissue.
• Calculating the time since death based on the decay rate of carbon-14.

This method is reliable for ages up to about 75,000 years, making it a valuable tool in archaeology.

archaeological dating methods

Archaeological dating methods are techniques used to determine the age of artifacts and archaeological sites. One prominent method includes radiocarbon dating, using carbon-14 to date organic materials. This method has revolutionized the field of archaeology by allowing precise dating of objects that are thousands of years old.

Some other common archaeological dating methods include:

• Tree-ring dating (Dendrochronology): This provides calendar-year dates to wooden objects based on the comparison of growth rings.
• Thermoluminescence dating: Used to date ceramics by measuring the light emitted when the sample is heated.
• Potassium-argon dating: Useful for dating volcanic rock.

These methods help archaeologists build a clearer timeline of past human activity, providing insights into historical events and the development of civilizations.