AC Vocabulary Chapter 6 Section 3

Absolute Dating Any method of measuring the age of an event or object in years

Isotope An atom that has the same number of protons as other atoms of the same element but a different number of neutrons.

Radioactive Decay The process in which a radioactive isotope tends to break down into stable isotopes of the same element or another element.

Parent isotope An unstable radioactive element

Daughter Isotope The stable isotope produced by the radioactive decay of the parent isotope.

Radiometric Dating A Method used of determining the age of an object by estimating the relative percentages of unstable radioactive (Parent) isotopes and stable radioactive (Daughter) isotopes found in the object.

Half Life The time needed for half of a sample of radioactive substance to undergo radioactive decay.

4 Types of Radiometric Dating 1. Potassium Argon Method- Parent isotope is Potassium-40 Has a half-life of 1.3 billion years. Decays into argon and calcium Daughter isotope is argon. Used to date rocks older than 100,000 yrs. 2. Uranium-lead method- Parent isotope is uranium-238, Half life is 4.5 billion years. Daughter isotope is Lead 206. Used to date rocks more than 10 million years old. Generally used to date Earth’s oldest rock. 3. Rubidium-Strontium method- Parent-Rubidium-87, Half life- 49 billion years, daughter- strontium-87- also used to date rocks that are 10 million years old. 4. Carbon 14 Method- Half life is 5,730 years. Used for dating things that lived within the past 50,000 years.