RadioMetric Dating for dummies!

1. What is the different between 12C, 13C and 14C? Which is the most unstable? What is the half-life of 14C?

The difference between 12C, 13C and 14C is the number of neutrons each carbon atom contains, 12c holds 6 protons and 6 neutrons, 13C contains 6 protons and 7 neutrons, and lastly 14C has 6 protons and 8 neutrons. Carbon 14 would be the most unstable due to the fact that the atom will have to break down twice before it becomes a stable 12C atom. The half life of 14C is 5,730 years.

2. What are some other radiometric decay systems (besides carbon-14) that are useful for determining the ages of evens in Earth’s history?

There are three other radiometric isotopes that could help to determine the ages of rocks and minerals within the earth. The first is rubidium, then as rubidium breaks down it become strontium these two can provide a good source of radioactive dating. Another isotope is the ever classic uranium which breaks down into its stable form over many millions or in some cases billions of years. All three provide a type of scale that can be used.

3. Why don’t stable elements have half-lives?

Stable elements do not have half-lives because they have no need to break down, Atoms that have different amounts of protons and neutrons are always trying to get to a stable equal element therefore they have to break down to get there, this act of breaking down has a amount of time connected to the process, thus you have the half-live of that break down time.

4. Write a short dialogue between you and a 12-year old friend explaining Figure 3.1

Child: What is this picture Uncle Joshua? Me: Well Timmy in this picture scientists are trying to explain how they can use the breakdown of minerals inside a rock to tell how old it is. The scientists know that when the rock is formed there can be no added source of the radioactive mineral added so they can then measure the breakdown of the atoms/ isotopes that exist inside the rock. Child: What do the Dots mean in the middle of the rock? ME: The dots in the middle of the rock highlight sections in a counterclockwise in which the scientists can watch and measure the breaking down of the atoms. Child: Oh cool, so they can find out how old dinosaurs are just by looking at the rocks around a fossil? Child: Yes, Timmy that is the idea. Child: That’s what I want to do when I grow up! ME: Tell your parents to start saving for your college education now!

5. How do we calculate the absolute of fossils?

Scientist calculates the ages of the ash layers around, above, and below a given fossil to get an accurate estimate the age of that given fossil.

Source:

Zimmer, C. (2010). The Tangled bank: an introduction to evolution. Greenwood village, CO, USA: Roberts and company publishers.