## Presentation on theme: "Radioactive Dating with Carbon"— Presentation transcript:

This ISN’T what radiocarbon is, but it’s kinda funny…

A technique that can determine an age of an object by examining its chemical composition.

What do you think is meant by the term ‘radioactive’?
The atoms are hot and glowing The atoms have an unstable nucleus The atoms will chemically bond with anything The atoms move very fast

An atom with an unstable nucleus. Over time, a radioactive nucleus will break apart and in the process emit radiation (that’s where the ‘radio’ part of the name comes from) and a particle.

Radioactive Carbon Most carbon on earth is not radioactive. Only about 1 in every TRILLION atoms of carbon is radioactive. When radioactive carbon breaks down, it becomes Nitrogen which is a stable atom.

Why is radioactive carbon in many ecofacts (like bones, pollen, wood, etc)?
Radioactive carbon is in air in the form of Carbon Dioxide. Plants take in small amount of radioactive carbon when they perform photosynthesis Animals eat the plants that have the radioactive carbon.

The half life for radioactive carbon is 5,730 years.
Studies on radioactive atoms show that they always break down in a pattern like this: 50% of the radioactive atoms in a sample will breakdown in a given time period called a half-life. The half life for radioactive carbon is 5,730 years.

TRY THIS: How many half lives has an object gone through if 25% of its carbon is still radioactive? Click in your answer.

TRY THIS: If 25% of an object’s carbon is still radioactive, and the half-life of radioactive carbon is 5,730 years, how old is the object? Click in your answer.

TRY THIS: Suppose you find an object that is 12.5% C-14 and 87.5% N-14. How old is the object if the half life of C-14 is 5,730 years?

I’m going to get a T-Shirt like this for my daughter when she grows up…

OUR SIMULATION: Count beans for one artifact or ecofact.
Report your counts of white & black beans on the board. Calculate the age of your artifact or ecofact. Copy down a bean count for each of the other artifacts/ecofacts. Calculate the age of each sample. Write out answers to the questions.