Curiosly enough, element number 2 was discovered on the Sun before it was discovered on Earth. That’s why its called Helium. It was discovered by optical spectroscopy. It’s hard to detect on Earth because it is a rare gas and doesn’t form stable compounds.
(Hope I didn’t miss this in an above post)
If we do find a set of elements after (in?) the island of stability, is there any chance sufficient quantities could be made to find an industrial use? I realize this probably depends on how the elements would be created, but I assume there are theoretical models for doing so.
Rhythmdvl:
The wiki article seems to talk in terms of possible half lives on the island as possibly lasting hours, as opposed to milliseconds. By way of comparison, Mendelevium which has a half life as long as 52 days, has no practical use according to my cite.
Dumb question: What happens after radioactive decay? Do all these elements turn into lead eventually, after a number of intervening steps?
Most turn into an isotope of lead, but some turn into bismuth or thallium.
This. Elements typically decay by emitting either an alpha or a beta particle, though some of the higher transuranics prefer to decay by fission instead. A variety of nuclides of various elements are produced by the fission decay.
If an isotope is too neutron-rich for stability, it decays by emitting a beta particle, a fast-moving electron, from the nucleus. Where the nucleus gets an electron is, a neutron spontaneously transforms into a proton, an electron, and an antineutrino. The effect is to keep the atomic mass essentially stable but move it up one notch on the periodic table, so that U-239 decays into Np-239, which itself quickly beta-decays into Pu-239.
An isotope which is too neutron-poor for stability, on the other hand, tends to give off an alpha particle, a fast-moving helium nucleus, lowering its atomic mass by 4 and its atomic number by 2. Ra-226 typically gives off an alpha particle to become Rn-222, if I remember correctly.
This means that decay chains shift along the periodic table while maintaining an esentially stable atomic mass, or drop down the table with a mass loss of 4 and an atomic number loss of 2. Since the shifts occur in multiples of 4, four distinct decay chains are possible, with three extant.
The one characterized by even multiples of 4 starts with the decay of Th-232; all its members are even multiples of 4, and it ends with Pb-208.
The 4n+2 decay sequence starts with U-238, and ends with PB-206. The 4n+3 series begins with U-235 and ends with PB-207.
The 4n+1 series is no longer extant, owing to the shorter half-life of its parent, Np-237. But it decayed to Bi-209.
Side branches of these, involving statistically rare alternate breakdowns (beta instead of the more normal alpha, positron emission for a reverse beta, etc.) lead to Pb-204, Tl-203, or Tl-205, or even isotopes of mercury.
I’m not sure what you were trying to say in the first half of this sentence. Can you rephrase this?
In case Polycarp is sleeping: A nucleus doesn’t have any electrons to emit. To get an electron, a neutron decays into a proton, electron, and antineutrino, emitting the electron and antineutrino.
I thank Polycarpe for expanding on my answer in an interesting post.
To answer the question about how the earth got its elements, here is a crude answer. The early universe consisted roughly of 75% hydrogen, 25% helium and perhaps a small trace of lithium. Stars produced by exothermic fusion all the elements up to iron. But iron has, percentagewise, the least binding energy and no more energy can be produced by fusing iron. But sufficiently massive stars (I think any star about 2 1/2 times the mass of the sun) will undergo catastrophic collapse and then explode into a supernova. Some of the gigantic amound of gravitational energy released in that collapse produces all the elements with atomic numbers higher than iron. But these are mostly blown out into space leaving perhaps a neutron star or a black hole. Meantime the debris joins the hydrogen clouds from which new stars and planetary systems form and these are born with whatever heavy elements went into the mix. Planets like earth are just not massive enough to keep much hydrogen and helium and so wind up being made mostly of heavier elements. Fractional distillation explains why you find concentrations of some elements. The earth’s core is thought to be mostly nickel and iron, if only we could mine it.
Exactly. (I was up really late, and slept in; thanks for handling this.) There are no electrons in a nucleus – when one is emitted in beta decay, it’s produced an instant prior to the time of emission as Zen Beam outlined.
Rarely, a “reverse beta” will occur in which a proton turns into a neutron, emitting a positron and something neutrino-ish (I think still an electron-antineutrino, but memory is not clear on this).
We now have an answer 11 years later: