Geological Dating Part II Absolute

Absolute Age Dating This method enables scientists to determine the actual age of a rock Radioactive isotopes are found in…. Found in…. in igneous & metamorphic rock and also some fossils and organic remains. fossil or object using the decay rate of radioactive isotopes. (rock formed from magma and rock formed by tremendous heat and pressure) igenous & metamorphic

Comparing Relative to Absolute (Numerical) Difference between relative and absolute

Radiometric Dating- Rocks A radioactive isotope will break down into lighter elements and will give off radioactivity in the process. This is the process by which scientists determine the ratio of parent nuclei to daughter nuclei within an object. A half life is the period of time for one half of the elements atoms change to another element. The emission of radioactive particles and the resulting change into other elements over time is called radioactive decay The rate of decay of a radioactive element is measured by its half-life Radioactive substance emit nuclear particles at a constant rate Define Ratio Rate The original radioactive element is called the parent and the new element is called the daughter

Radioactive decay of uranium Radon is an invisible, odorless gas that is a natural radioactive decay product of uranium, a common element in soil and rocks. Radon gas is considered harmless when dispersed in outdoor air but can be a serious health hazard when trapped in buildings.

Once emission of these atomic particles begins, the rate remains constant regardless of any physical changes. Therefore, these particles become accurate indicators of the absolute age of an object. Each radioactive element had different half lives.

Half-Life At the end of 1 half-life what is the relationship of daughter to parent material? If 2 rocks were found one containing 2 g of A and the other 4 g of A which rock is older? What percent of the sample is Daughter B at 4 Half-Lives? At the end of one half life the amount of parent material = daughter material In each succeeding half life half of the remaining atoms decay

Clocks in Rocks What is the percent of atoms of the parent and daughter element at a half-life of…? 1, 2 & 5 How can a scientist determine the actual age with this information? Now you are ready to click on: http://www.sciencecourseware.org/VirtualDating/files/1.0_ClocksInRocks.html 1-50% each 2-25% parent and 75% daughter 5- 3% parent and 97% daughter

Once Living things Interpret Evidence Direct Evidence of past Fossils Once Living things Interpret Evidence Direct Evidence of past

Radiocarbon Dating - Organisms Carbon C-14 is changed into Nitrogen N-14 during decay of living organisms. Now try this: http://www.sciencecourseware.org/VirtualDating/files/RC0/RC_0.html

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