Radiometric dating exam questions

As a result I was using some of my texts to examine the decay of Americium 241 and noted the naturally occurring decay chains for U235, U238 and Th232, as well as the fully decayed chain for Pu241.

My thought is, can the relative natural abundances of these chains' terminal products (Pb208,207, and 206) be used to calculate an initial abundance and time frame for the original atomic abundances of the parent isotopes which could be compared to the predictions of Willie Fowler regarding stellar nucleogenesis processes. Thanks again for all your interesting and informative web postings and work.

As far as stars are concerned, the Th/Nd ratio has been shown to be unchanged no matter what the age of the star is, which leads one to two conclusions.

Choose your answers to the questions and click 'Next' to see the next set of questions.

You can skip questions if you would like and come back to them later with the yellow "Go To First Skipped Question" button. Choose your answers to the questions and click 'Next' to see the next set of questions.

Furthermore, there is evidence that the main radioactive elements were concentrated in a layer low in the mantle and came to the surface progressively after that.

I emailed you about this topic a year or two ago, and I've since taken a class in radioisotope chemistry at UCI.

• The decay constant is unique for each radioactive element. The Decay Constant,  • Some values of the decay constant: • C14: 1.21x10-4 atoms per year • U235: 9.72x10-10 atoms per year • K40: 5.34x10-10 atoms per year Calculating a Half Life • t = (ln (P D)/P)/  • What is the half life of Carbon-14?

• t = (ln ((1 1)/1))/1.21x10-4 • t = (ln 2)/1.21x10-4 • t = 5,730 years Some Half Lives • Carbon-14: 5,730 years • Uranium-235: 704 MY • Potassium-40: 1.3 BY • Uranium-238: 4.5 BY • Rubidium-87: 48.8 BY Calculating a Radiometric Date • t = ln (P D)/P (P D = starting material) l • An ash bed just above the Dev.- Carb.

• Individual crystals of the same mineral are dated to give the age of crystallization or cooling. • Note that whole rock analysis would not give the age of cooling.

Setting the Radiometric Clock • Carbon-14 is different in that it occurs in organic remains rather than in rocks. • Carbon-14 is absorbed by all living organisms from the atmosphere or the food they eat.

Basis of the Technique • Radioactive elements “decay.” Decay occurs as an element changes to another element, e.g. • The parent element is radioactive, the daughter element is stable. • Usually protons and neutrons are emitted by the nucleus. • Carbon-14 is produced by cosmic ray bombardment of Nitrogen-14 in the atmosphere. Doesn’t matter how many atoms started, half will decay.

Tags: , ,