- Silentone2
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- Fabled Mythic Member
OMG
Master Chief w/o his Helmet!
Stosh <3's me vicariously... at least someone does...
To address what I believe is the spirit of your question, I'll try to explain the concept of the Mass Defect.
The traditional model of the atom is a cloud of electrons surrounding a much smaller (smaller radius than the cloud) nucleus made of protons and neutrons, which constitute the bulk of an atom's mass.
It was discovered that the mass of the nucleus was less than the protons and neutrons it was made of. That is to say, if you had a given number of protons and neutrons and summed all their masses individually, the number you would get would be larger than the mass of an nucleus comprised of an equal number of protons and neutrons.
This "Mass Defect" represents the conversion of some mass into Binding Energy; which you can think of as the "strength" of the nuclear forces holding the atom together. Likewise, this is the amount of energy it would take to destroy the atom.
(Edit: as others have pointed out, the conversion can be modeled by the famous Energy=Mass*(Speed of Light in Vacuum)^2)
Not all of the energy "lost" goes into Binding energy however. If an atom "doesn't need" that much energy to be bound, the excess energy can be released as radiation. Whether that radiation be comprised of photons or constituents of the atom depends on the type of atom and the amount of energy.
This is why fusion and fission are so powerful. In fusion, we convert mass into energy (which is released as radiation) by combining atoms. In fission, we break apart an atom, which splits into constituents with kinetic energy (they are moving). We take the kinetic energy from fission by letting these constituents crash into things.
A nuclear weapon can only be constructed reasonably out of certain atoms, and even then only certain isotopes of those atoms. The reason is that some isotopes are more unstable than others, and thus will produce more powerful fission events at lower energies. "Enrichment" is simply the separating of usable isotopes from less desirable ones (they are found together in nature).
With certain materials (such as U-235,233, or Pu-239), a fission "chain reaction" can occur, in which an addition of energy (via neutron collision) will cause some material to fission, and the neutrons released from this fission have enough energy to cause fission when they collide with more of the material.
In a nuclear weapon, this happens trillions of times over, and all that "extra" energy waiting in the Mass Defect becomes very, very, noticeable. Some fission weapons release so much energy (the "100,000,000 degrees" Cortana talks about in Halo 1), that they are capable of causing fusion, and thus apparatus are added to these weapons that allow the fission event to cause a fusion event, thus increasing the yield of the weapon. This is how the 50 MT Tsar Bomba was built.
Hopefully that cleared things up.
[Edited on 12.23.2012 3:45 PM PST]