Radiometric dating

High school (ages 12+)
Science & Technology

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Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/radiometric-dating

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the key isotope systems?Uranium-Lead (U-Pb), Potassium-Argon (K-Ar), Rubidium-Strontium (Rb-Sr), Carbon-14 (¹⁴C)
2. What is the primary application?Establishing absolute ages for geological formations and calibrating the geologic time scale
3. How do scientists know how old a rock is?They measure the ratio of parent to daughter atoms in the rock with a mass spectrometer. They also know the half‑life, the time it takes for half the parent atoms to change. With that information, they can work out how many years have passed.
4. Why can the clock inside a rock keep time no matter the temperature?The rate at which the radioactive atoms decay is a constant called the decay constant. It does not change with temperature, pressure, or the rock’s chemistry, so the clock stays reliable.

Decay Constant (λ): A measure of the rate at which a radioactive isotope decays.
Half-life: The time required for half of a radioactive isotope in a sample to decay.
Mass Spectrometry: A technique used to measure the mass-to-charge ratio of ions, essential for isotope analysis.