And a question about uranium dating... if the metal decays over a period of 4-5 billion years, then shouldn't there not be any unstable uranium on earth? Wouldn't it all have decayed and formed lead?How is uranium created? Only the elements up to iron can be fused inside a star?For the first part, I don't see why stars would be forced to stop at iron.
For the second part, most of the earths heavy metals were left here by other objects colliding with us in space after the planet was formed.How is uranium created? Only the elements up to iron can be fused inside a star?
Uranium-uranium dating is a radiometric dating technique utilizing the comparison of two isotopes of uranium (U) in a sample: 234U and 238U. 234U/238U dating is one of several radiometric dating techniques exploiting the uranium radioactive decay series, in which 238U undergoes 14 alpha and beta decay events while decaying to the stable isotope 206Pb. Other dating techniques using this decay series include uranium-thorium (using 230Th/238U) and uranium-lead dating.
238U, with a half-life of about 4.5 billion years, decays to 234U through emission of an alpha particle to an isotope of thorium (234Th), which is comparatively unstable with a half-life of just 24 days. 234Th then decays through beta particle emission to an isotope of protactinium, 234Pa. 234Pa decays with a half-life of 6.7 hours, again through emission of a beta particle, to 234U. This isotope has a half-life of about 245,000 years. The next decay product, 230Th, has a half-life of about 75,000 years and is used for the related 230Th/238U technique. Although analytically simpler than 230Th/238U dating, in practice 234U/238U dating is almost never used as unlike 230Th/238U dating it requires prior knowledge of the 234U/238U ratio at the time the material under study was formed. For those materials (principally marine carbonates) for which the initial ratio is known, 230Th/238U remains a superior technique. This restricts the application of 234U/238U to extremely rare cases where the initial 234U/238U is well-constrained and the sample is also beyond the ca. 450,000 year upper limit of the 230Th/238U technique.
How is uranium created? Only the elements up to iron can be fused inside a star?%26gt;How is uranium created? Only the elements up to iron can be fused inside a star?
Wrong. Only the elements up to iron can be fused with a net production of energy. Higher elements can be formed, they just require more energy than they produce in doing so. Very heavy elements (heavier than iron) were mostly produced in supernovas, where the extreme energy levels produced by the fusion of lighter elements also allowed for heavier elements to fuse in the same explosions.
%26gt;if the metal decays over a period of 4-5 billion years, then shouldn't there not be any unstable uranium on earth?
Elements do not decay over a specific time period, they decay according to a half-life. For example, uranium-238 has a half-life of about 4.5 billion years. That does NOT mean that it decays in precisely 4.5 billion years, all it means is that on average, half of a given quantity of it will have decayed by the time 4.5 billion years are up. Since the Universe is only 13.7 billion years old, we divide 13.7 by 4.5 and get 3.044, 0.5^3.044=0.1212, so if a quantity of uranium with n atoms had existed at the beginning of the Universe, approximately 12.12% would remain today, and in another 4.5 billion years, approximately 6.06% would remain, and so on. Since the Earth happens to be roughly 4.5 billion years old, about half of all the U-238 present on the Earth when it first formed has now decayed into lighter isotopes, because 4.5 billion years is roughly the half-life of U-238. At this rate, halving the amount every 4.5 billion years, it would take a very, very long amount of time (many trillions of years) for the U-238 present on Earth when it formed to ALL decay.
Also, why is this question in the Religion category?How is uranium created? Only the elements up to iron can be fused inside a star?
since everything is formed (according to astrophysics) from the dust of others stars, so is uranium and the heaviest of the elements. Only it is theorized that it would take a super massive star to create it in order to create the temps and pressures that smaller stars can not achieve. the material is cast out after their destruction and winds up in the formation of planetary bodies.
This theory has cast doubts in some scientific communities as to how our solar system was truly formed since they can not agree than the planets were formed from our own solar center because it is not capable of creating these elements.How is uranium created? Only the elements up to iron can be fused inside a star?Supernovas.
http://curious.astro.cornell.edu/questio…
http://www.noao.edu/outreach/press/pr00/…
http://www.pbs.org/wgbh/nova/origins/fab…
The half life of Uranium 238 is 4.47 Billion Years, so it can be used for radiometric dating from the beginning of the Earth.
http://en.wikipedia.org/wiki/Radioactive…
http://en.wikipedia.org/wiki/Uranium-lea…
The trans-iron elements are formed during supernovae.
The half-life of uranium-238 is 4.47 billion years. This means if you started with 1000 grams of it, after 4.47 billion years, you'd have 500 grams of it left. This means that Earth still has approximately half of the U-238 it started with.
How is uranium created? Only the elements up to iron can be fused inside a star?
Shouldn't this question be asked in the science section?
Uranium are created by stars, All of the elements are created by/in stars. Uranium don't decay into lead.
Edit: By/In Stars - Either directly through normal fusion inside the star or by a star (Ie. Gravitational collapse)
Wrong-o: In a supernova the excess energy from positive binding curve reactions powers negative binding curve reactions. Kinda like that waterfall in Colorado where the water descends a great distance before it ascends a modest distance. What you should worry about is why there is no native plutonium. How is uranium created? Only the elements up to iron can be fused inside a star?
Uranium is mined and obtained from the earth... we don't make it.
If you know about intelligent design, please help:
http://answers.yahoo.com/question/index?…
Elements heavier than iron are made in supernovae.
Its half-life is 4-5 billion years. That means that after 4 billion years, half of it has decayed and half is left.
I don't know how it works, i only use it
A reall good discussion on this is in
1) the Answers book by Answers in Genesis and
2) the RATE project DVD and book (Radio Isotopes and the Age of the Earth )
People who say Uranium is made in stars are saying so on faith in naturalism, not on the basis of evidense
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