Radioactive Dating Law of Superposition

Radioactive Dating

Chapter 6 Lesson 3

Multiple Choice

What does Absolute Dating mean?

• figuring out the age of something by putting it order from oldest to youngest.

• figuring out how old something is down to the day.

• using any method to find the age of an object in years

• using a method of counting layers of rock to understand the age of something.

Absolute Dating is what scientists use to understand things like the age of the Earth, the age of fossils, and the age of remains.

One absolute dating method is known as "Radiometric Dating"

isotope is an element with a different number of neutrons.

Multiple Choice

What does radiometric dating compare in an object?

• how many electrons it has

• the difference in the size of electrons

• the space between isotopes

• The amount of radioactive and nonradioactive isotopes.

What does it mean to be radioactive?

It means that the particle is unstable and is giving off energy.

This is an example of how this decay might be represented.

Notice the "Parent isotope" has particle leaving it. The other named particle is the "daughter isotope".

Multiple Select

When something is radioactive, it is doing what?

• giving off energy

• decaying

• breaking down

• turning into a stable element

Half-lives

When 1/2 of an element decays, this is known as a half life.

All unstable, radioactive, elements have a specific decay rate and it is unique to that element.

Multiple Choice

What does the term "half-life" mean?

• This is the amount of time it takes for something to decay completely.

• This is the amount of time it takes for half of a radioactive element to decay.

• This is the amount of time it takes for an element to become stable.

Figuring out the number of half-lives.

By looking at the percentage or fraction of element that has decayed you can determine how many half lives have gone by.

Multiple Choice

If the red represents the unstable isotope, how many half lives have gone by for this unknown element?

• 1

• 2

• 3

• 4

Multiple Choice

If the red represents the radioactive element, how many half-lives have gone by for this unknown element?

• 1

• 2

• 3

• 4

How many years?

After you know how many half-lives have occurred you simply multiply that number by the amount of time it takes for that element to decay.

Multiple Choice

Carbon 14 has a half life of 5,730 years. If there is 50% of the Parent Isotope left, how old is the sample?

• 5,730 years old

• 11,460 years

• 2,865 years

• 17,190 years

Multiple Choice

If a half-life of an element is 1,000 years and there is only 25% of it left, how many years old is the sample?

• 1,000 years

• 2,000 years

• 3,000 years

• 500 years

Multiple Choice

If you only have 6.25% left of a sample how many half-lives have gone by?

• 1

• 2

• 3

• 4

Multiple Choice

What is the name of the daughter isotope in this image?

• He4

• Alpha

• Beta

• Lead-208

Fill in the Blanks

When there is 87.5% daughter isotope in a sample, how much parent isotope is left?