Uranium-239 does NOT decay by alpha decay, it decays only by beta and gammadecay.
There are 3 naturally occurring isotopes of Uranium, all decay by alpha to Thorium:238U --> 234Th + 4He235U --> 231Th + 4He234U --> 230Th + 4He
The equation for the alpha decay of 233Pu:94233Pu --> 92229U + 24He2+where the alpha particle is represented as a helium nucleus.Note that 233Pu decays by alpha decay with a probability of only 0.12%. The other 99.88% is Beta+ decay.
The first step is an alpha decay to (guess what!) uranium 235. You can probably take it from there.
Uranium 238 is transformed in thorium 234 by alpha decay.
The equation for the alpha decay of 233U is: 92233U --> 90229Th + 24He representing the alpha particle as a helium nucleus. 223U can also undergo fission, but since this is an rather unpredictable process, there is no standard equation.
The equation for the alpha decay of 235U is: 92235U --> 90231Th + 24He representing the alpha particle as a helium nucleus. 235U also decays by spontaneous fission, but the results are somewhat unpredictable, so there is no standard equation.
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If a uranium-244 atom undergoes alpha decay, it will become an atom of thorium-240. If we wrote an equation, it might look like this:92244U => 90240Th + 24He++The uranium-244 is transmuted into throium-240, and the alpha particle, which is a helium-4 nucleus (and represented as such) emerges at the tail end of the equation.
The equation for the alpha decay of 226Ra: 88226Ra --> 86222Rn + 24He The alpha particle is represented as a helium (He) nucleus.
The only possible product of the alpha decay of 92238U is 90234Th.