1 / 6

Tips on Dating

Tips on Dating. Why Date?. Different methods of dating will help determine the actual age of a layer of rock or a fossil Scientists look at how much radioactive isotopes are left after years of decay

Télécharger la présentation

Tips on Dating

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Tips on Dating

  2. Why Date? • Different methods of dating will help determine the actual age of a layer of rock or a fossil • Scientists look at how much radioactive isotopes are left after years of decay • Radioactive isotopes are isotopes that have have a different number of neutrons compared to the original element and give off radiation • Eventually, they break down into more stable isotopes through radioactive decay

  3. Parents vs. Daughters • The radioactive isotope is also called the parent and is unstable, giving off radiation • The parent decays and changes into a more stable isotope called the daughter • To figure out the age of a rock or fossil, scientists compare the amount of parent and daughter • The more daughterthere is, the older the rock or fossil is!

  4. Half-Life • By knowing the rate of decay of a radioactive isotope, the age can be determined. This is called its half-life, which is the time it takes for half of the radioactive isotope to decay into the daughter • With each half-life, the amount of parent remaining is cut in half • The three most common radioactive isotopes are uranium-238, potassium-40, and carbon-14

  5. Common Radioactive Isotopes & Their Daughters • Uranium-238 decays into Lead-206. Uranium’s half-life is 4.5 billion years, which means it takes 4.5 billion years for half of the uranium to decay! • Potassium-40 decays into Argon-40. Potassium’s half-life is 1.3 billion years. • Carbon-14 decays into Nitrogen-14. Carbon’s half-life is 5,730 years. Since all living things contain carbon, this method is used most often for organisms that lived within the last 50,000 years.

  6. More About Half-Lives • After 1 half-life, there is 50% (1/2) parent, 50% daughter • After 2 half-lives, there is 25% (1/4) parent, 75% daughter • After 3 half-lives, there is 12.5%(1/8) parent, 87.5% daughter • After 4 half-lives, there is 6.25% (1/16) parent, 93.75% daughter

More Related