110 likes | 229 Views
Science Notes. Absolute Dating. What is absolute dating?. A process of establishing the age of an object by determining the number of years it has existed. What are isotopes?. Atoms of the same element that have the same number of protons but have different numbers of neutrons.
E N D
Science Notes Absolute Dating
What is absolute dating? • A process of establishing the age of an object by determining the number of years it has existed.
What are isotopes? • Atoms of the same element that have the same number of protons but have different numbers of neutrons.
What does radioactive mean? • It’s a term that applies to unstable isotopes.
What is radioactive decay? • The process by which unstable isotopes tend to break down into stable isotopes of other elements.
How do scientists use radioactive decay to determine an object’s age? • Since radioactive decay occurs at a steady rate, scientist can measure the amount of unstable isotope (parent material) and the amount of stable element (daughter material) and calculate how old the object is.
What is radiometric dating? • Determining the absolute age of a sample based on the ratio of parent material to daughter material.
What is half-life? • The time it takes for one-half of a radioactive sample to decay.
What are some examples of radiometric dating methods? • Uranium-Lead Method • Used on rocks more than 10 million years old. Uranium 238 (parent) has a half-life of 4.5 billion years and decays to lead-206 (daughter).
What are some examples of radiometric dating methods? • Potassium-Argon Method • Used on rocks older than 100,000 years. Potassium-40 (parent) has a half-life of 1.3 billion years and decays to argon (daughter).
What are some examples of radiometric dating methods? • Carbon-14 Method • All living things have a balanced amount of carbon-14 and carbon-12. Once the organism dies the amount of carbon-14 begins to decrease with a half-life of 5,730 years. The ratio of carbon-14 to carbon-12 left in the sample can be measured to calculate the age. Used for dating things that lived within the last 50,000 years.