Radioactive Decay and Half-Life Concepts

This tutorial explains how to calculate the age of a rock using parent and daughter isotope ratios. It introduces the concept of absolute age, which provides an exact number based on radioactive decay, a constant process. The tutorial details the use of half-life, the time it takes for half of the parent isotopes to decay into daughter isotopes. Through examples, it demonstrates how to calculate the number of half-lives that have passed and how to use this information, along with the known half-life of the isotopes, to determine the age of a rock sample.

What is the primary method used to determine the absolute age of a rock?

• Radioactive decay

• Stratigraphy

• Fossil analysis

• Carbon dating

What is a half-life in the context of radioactive decay?

• The time it takes for isotopes to disappear

• The time it takes for all parent isotopes to decay

• The time it takes for half of the parent isotopes to decay into daughter isotopes

• The time it takes for daughter isotopes to become stable

In the example problem, how many total atoms are there initially?

• 1000

• 750

• 500

• 1250

After one half-life, how many parent isotopes remain in the example?

• 1000

• 500

• 750

• 250

How many half-lives have passed when there are 250 parent isotopes left?

• Four

• One

• Two

• Three

What is the known half-life of the hypothetical parent-daughter isotope series in the example?

• One million years

• Two million years

• Three million years

• Four million years

How old is the rock sample if two half-lives have passed and the half-life is two million years?

• Five million years

• Four million years

• Three million years

• Two million years

What is the total number of atoms after three half-lives in the example?

• 1250

• 1000

• 875

• 750

What happens to the number of daughter isotopes as more half-lives pass?

• It remains the same

• It fluctuates

• It decreases

• It increases

Why can't atoms be split in half during the calculation of half-lives?

• Atoms can only be split in nuclear reactions

• Atoms are indivisible

• Atoms are too small to measure

• Atoms are stable