Uranium and uranium dating.pptx

Uranium
Uranium dating method

1. Uranium and Uranium Dating

2. Uranium “ Uranium is a heavy, silver-grey, radioactive metal, used mainly in producing nuclear energy.” It is a silvery-grey metal in the actinide series(14 in No - atomic numbers 89 and 103 ) of the periodic table. A uranium atom has 92 protons and 92 electrons. Melting point of Uranium  is 1132°C . Boiling point of Uranium is 3818°C.  2

3. 3

4. 4 Uranium was discovered in 1789 by a German Chemist Martin Klaproth. He named his discovery “uran” after the planet Uranus. History

5. Physical Properties 5 It is the most common heavy element in the Earth’s crust .   Uranium is a  hard, dense, malleable, ductile, radioactive metal . It is a poor conductor of heat and electricity.  

6. 6 Occurrence Traces of it occur almost everywhere. It is more abundant than gold, silver or mercury. The Earth's crust from surface to 25 km down contains 100 trillion tons of Uranium, and the ocean contains 10 billion. Uranium was formed over 6.6 billion years ago. Uranium occurs naturally in the Earth's crust, water, air, and living organisms, Rocks ( igneous, metamorphic or sedimentary rocks ).

7. 7

8. 8 The rocks of Siwaliks of the Potwar Plateau, Northern Pakistan. Bannu Basin Dera Ghazi Khan Issa Khel and Kirther Range Suleiman range up to the Arabian Sea in the west have been extensively explored for uranium. ballistic missiles: the short-range Abdali (Hatf-2), Ghaznavi (Hatf-3), Shaheen -I (Hatf-4), and NASR (Hatf-9), and the medium-range Ghauri (Hatf-5) and Shaheen -II (Hatf-6).

9. Uranium Dating 9 A method of dating archaeological or geological specimens by determining the decay activity of the uranium in a given sample. Uranium dating is the oldest method of isotopic dating in which we can determine the age of organic materials using the radioactive chemical element Uranium. There are three different types of this technique: Uranium-Uranium method Uranium-Thorium method Uranium-Lead method . Among them, Uranium-lead method is the oldest method. But, it gives the most accurate results though it has a high risk.

10. 10 Methods of Uranium Dating

11. 11 1. Uranium-Uranium Method Uranium–uranium dating is a radiometric dating technique which compares two isotopes of Uranium (U) in a sample: Uranium-234  ( 234 U) and Uranium-238  ( 238 U). It is one of several radiometric dating techniques exploiting the Uranium radioactive decay series, in which  238 U undergoes 14 alpha  and beta decay  events on the way to the stable isotope  206 Pb. Other dating techniques using this decay series include Uranium-thorium dating and Uranium-lead dating .

12. 12

13. 13 2. Uranium-Thorium Method A relatively short-range dating technique is based on the decay of uranium- 234 into thorium-230, a substance with a half-life of about 80,000 years . It is accompanied by a sister process, in which uranium-235 decays into protactinium-231, which has a half-life of 32,760 years. While uranium is water-soluble , thorium and protactinium are not, and so they are selectively precipitated into ocean-floor sediments, from which their ratios are measured.

14. 14 3. Uranium-Lead Method Uranium-238 is a radioactive isotope that decays in a series of steps to lead-206.The half-life of uranium-238 is 4.5 billion years. The decay series ends with lead-206, which is stable. The older the rock is, the more daughter material (lead-206) there will be in the rock. Uranium-lead dating can be used for rocks more than 10 million years old. Younger rocks do not contain enough daughter material to be accurately measured by this method.

15. 15

16. 16

17. 17 Uses of Uranium Dating Uranium–lead dating , abbreviated U–Pb dating, is one of the oldest and most refined of the radiometric dating schemes.  It can be used to date rocks that formed and crystallized from about 1 million years to over 4.5 billion years. A Canadian research team has used a new uranium-lead (U-Pb) dating technique to show that a fossilised dinosaur bone found in New Mexico is only 64.8 million years old , meaning the creature was alive about 700,000 years after the mass extinction event that is believed to have wiped out all non-avian dinosaurs.

18. 18 Uranium-238 _ Uranium-238 dating, method of age determination that makes use of the radioactive decay of uranium-238 to uranium-234; the method can be used for dating of sediments from either a marine or a playa lake environment. Uranium decays through a number of radioactive daughter isotopes, some of which have half-lives comparable to the time scale of prehistoric archaeology . The growth of these isotopes in naturally occurring materials at archaeological sites can be used to determine the age of sites. Uranium–lead (U-Pb) dating: Measures the ratio of two lead isotopes (Pb-206 and Pb-207) to the amount of uranium in a mineral or rock. Uranium–thorium (U- Th ) dating: This technique is used to date speleothems, corals, carbonates, and fossil bones. Its range is from a few years to about 700,000 years.

19. 19

20. 20