Activity 8 3 absolute dating of rocks and fossils

For each bag, count a specific number of "parent isotope" beads of one color and "daughter isotope" beads of another color.

Once you have a set of parent and daughter isotope beads in the bag, fill up the bag with a mixture of all the other colors.

The atom's nucleus is composed of protons and neutrons, which are much more massive than electrons.

When an element has atoms that differ in the number of neutrons, these atoms are called different isotopes of the element.

Each isotope is identified with what is called a ‘mass number’.

When ‘parent’ uranium-238 decays, for example, it produces subatomic particles, energy and ‘daughter’ lead-206.

Each atom has a positively charged nucleus surrounded by negatively charged electrons.

As scientists, their job is to count the number of parent and daughter isotope atoms in each bag, and from this data to determine how many half-lives the isotope has gone through and therefore the age of the rock.

A good idea is to have the graph printed on the worksheet with the data table so that the students can have it right in front of them.

Geologists often need to know the age of material that they find.

Current methods include using the known decay rates of radioactive isotopes present in rocks to measure the time since the rock was formed.

Before class begins, prepare five bags filled with about 100 beads each.

Activity 8 3 absolute dating of rocks and fossils