Uranium to lead. Transition/decomposition and half life...

[Shadow_Demon]

How does one element, uranium say, decompose into another (through a few more elements) -- ultimately lead?

[Clanad]

Ah... that's better, don't you agree?

Firstly, when Uranium in it's natural occurrence is discussed, inadvertently, U-238 is usually referenced, since it is the most abundant percentage of the mineral. However, U-234 and U-235 are Isotopes of U-238. Isotopes of an element have the same number of protons in the nucleus, but a different number of neutrons.

One major difference of importance in our discussion revolves around the fact that while U-238 has a half-life of 4.3 billion years, U-235 is about 700,000 years and U-234 is a mere 250,000 years or so. Each of these are radioactive, which means the nuclei spontaneously disintegrate or �decay.� (Source: U.S. Department of Energy Office of Depleted Uranium Hexafluoride Management Program. This "decay" consists of alpha particles (a collection of two protons and two neutrons) and gamma rays (an electromagnetic energy wave) (ibid.
The rate at which the nuclei in an isotope sample decay is called activity, which is the number of disintegrations (or emissions) that occur per second, which can then be calculated to determine the half-life of the element.

Contd.

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[Clanad]

Contd.

(A half life is the amount of time it takes for half or 50%, of a sample to decay. After that one half life, 50% remains; so after two half lives, 25% remains, since that's half of 50%, and onward until depletion occurs.)

In the process of decay, the radioactive Uranium 238 decomposes into:
thorium
Strontium
Rabideum
Potasium
Argon
and finally lead (Pb)206 [no longer radioactive]

There are some very short lived isotopes, such as Polonium 218 with a half-life of three minutes, give or take a few seconds... But more amazing is Polonium 214 whose half-life is 0.00164 seconds! (Let's not even talk about Polonium halos in granite).

So... there you have it in layman's terms... Thanks for the question...

[Shadow_Demon]

Thanks for the answer, good stuff. I was puzzled as to how one element can "morph" (haha) into another one. This answered it very clearly, much appreciated.