The smallest amount of material that can sustain a chain reaction. :)
The smallest amount of a fissionable material that will produce a self-sustaining chain reaction is called the critical mass. This mass of affected by geometry and other factors such as temperature, pressure, and moderator.
The critical mass. With an amount of U-235 or Pu-239, the smallest critical mass will be a sphere. For a nuclear reactor, it will be the minimum number of fuel assemblies loaded to produce a chain reaction.
The critical mass
Critical mass is the minimum amount of nuclear material needed to cause a chain reaction to continue without stopping.
We know that critical mass can be achieved in a nuclear reactor. If it could not, we'd not be able to get a chain reaction and generate heat to generate power. Reactors don't have critical mass when the control rods are in, but pull the rods, start the reactor up and away you go!
The critical mass.
Critical Mass is that minimum amount of fissionable material needed to maintain a chain reaction
If the universe is ever to stop expanding and start contracting there has to be a certain amount of material (mass). This amount is called the 'critical density'. So far as is known to date the universe does not have sufficient mass to stop expanding, hence it is below the critical density.
If it's a molecular compound, the smallest amount would be one molecule. If it's an ionic compound, the smallest amount is a formula unit.
This amount is the molecule.
The words fissile and fissionable are not generally taken to mean the same thing. Fissile materials can sustain a chain reaction with low energy neutrons. Fissionable materials can sustain a chain reaction, but only if the energy of the neutrons present is sufficiently high. Critical mass is the amount of material needed, in ideal circumstances, to start a chain reaction without neutrons other than those produced internally. 235U is fissile, and has a critical mass of 52 kg. 238U is fissionable, but there is no critical mass because no amount of uranium-238 suffices to produce a chain reaction. A mix of 235U and 238U can have critical mass, depending on the percentage of 235U present. Natural deposits of uranium do not have a high enough percentage of 235U to produce critical mass, even if the uranium is purified. But by removing some of the 238U, we produce enriched uranium, which can achieve critical mass. The lower the percentage of 235U present, the higher the amount needed to have a chain reaction. Other materials present also increase the amount needed, as do such things as the shape of the mass. The minimum amount for a critical mass is a pure sphere. You can decrease the critical mass by surrounding the material with something that reflects neutrons. Strictly speaking, however, the amount of fissionable material does not determine a likelihood of a chain reaction. You have enough fissile material, or you don't, so it is not a matter of likelihood.
The amount of material in a substance is mass.
This amount of material is the mass.
their is no radioactive material in the construction of any bomb its just a bunch of atoms creating friction and being so excited that they explode in a devistating amount of force.
The amount of one material in a certain volume of another material?
Solubility measures the amount of one material that will dissolve in another material.