# Line graphs and radiometric dating for dummies

### Line Graphs And Radiometric Dating

Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old. Chart of a few different isotope half lifes. Radiometric dating (often called radioactive dating) is a way to find out how old something is. Plotting an isochron (straight-line graph) is used to solve the age equation graphically. "Basics of radioactive isotope geochemistry" (PDF). Bag of: M&M's ®, pennies or, puzzle pieces; Paper – ˝ x 11˝; Graph Paper To model the rate of radioactive decay; To create line graphs from collected data To understand how radioactive decay is used to date archaeological artifacts.

She can then look her value up in a glossary of known radioactive decay constants to figure out which isotope is in her sample.

### Graphing Half Life WS

Another type of graph that scientists like to use to show nuclear decay data is a semilog plot shown below Mass versus time graph, with the half-life indicated by a red dot. Semilog plots are pretty tricky because the vertical axis has funny spacing.

- Line Graphs And Radiometric Dating
- In the Classroom
- Radiometric dating

In the plot above, appears to come halfway between 10 and So when we read the slope on a semilog plot, we need to remember to always take the logarithm of whatever values we read off the vertical axis. The slope of the line on the semilog plot corresponds to the same decay constant k, that we can identify in a normal exponential decay plot.

Finding the slope of straight lines, however, is generally much easier. By plotting data on semi-log plots, the scientist can better compare and identify different isotopes. Further information about an unknown radioactive isotope can be identified simply by analyzing the radiation that it shoots out of the isotope. Gamma radiation produces photons, beta decay produces electrons or positrons, and alpha decay releases entire alpha particles helium nuclei.

What is a half-life? Half-life is defined as the amount of time it takes for half of an isotope to change into another isotope.

Like the decay constant, the half-life tells us everything we need to know to guess what kind of isotope we might have. It even turns out that the two numbers are equivalent if you correctly solve the radioactive decay equation.

This means that, like the decay constant, the half-life gives an estimate of the stability of a particular radioactive substance, and it can thus be used to identify unknown isotopes. The primary reason that scientists use half-lives instead of decay constants is because half-lives have a more intuitive immediate meaning: Consider the following… carbon dating Most living things contain carbon, an unstable isotope of carbon that has a half-life of around 5, years. Radioactive materials contain some nuclei that are stable and other nuclei that are unstable.

## Decay graphs and half lives article

Not all of the atoms of a radioactive isotope radioisotope decay at the same time. Rather, the atoms decay at a rate that is characteristic to the isotope. The rate of decay is a fixed rate called a half-life. The half-life of a radioactive isotope refers to the amount of time required for half of a quantity of a radioactive isotope to decay.

Carbon has a half-life of years, which means that if you take one gram of carbon, half of it will decay in years.

### Decay graphs and half lives article (article) | Khan Academy

Different isotopes have different half-lives. The ratio of the amounts of carbon to carbon in a human is the same as in every other living thing. After death, the carbon decays and is not replaced. The carbon decays, with its half-life of 5, years, while the amount of carbon remains constant in the sample. By looking at the ratio of carbon to carbon in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing.

Radiocarbon dates do not tell archaeologists exactly how old an artifact is, but they can date the sample within a few hundred years of the age.

## Line Graphs

Have the students spill out the candies onto a flat surface. Have the students record the number of candies they returned to the bag under the next Trial. The students should move the candies that are blank on the top to the side — these have now decayed to a stable state. The students should repeat steps 2 through 5 until all the candies have decayed or until they have completed Trial 7. Set up a place on the board where all students or groups can record their data.