an alpha particle has a mass number of 4u.
an alpha particle has a mass number of 4u.
an alpha particle has a mass number of?
4u
Na
Na
where formula_2 is the initial mass of the nucleus, formula_3 is the mass of the nucleus after particle emission, and formula_4 is the mass of the emitted particle, shows that alpha particle emission will usually be possible just with energy from the nucleus itself, while other decay modes will require additional energy. for example, performing the calculation for uranium-232 shows that alpha particle emission would need only 5.4 mev, while a single proton emission would require 6.1 mev. most of this disintegration energy becomes the kinetic energy of the alpha particle itself, although to maintain conservation of momentum part of this energy becomes the recoil of the nucleus itself. however, since the mass numbers of most alpha emitting radioisotopes exceed 210, far greater than the mass number of the alpha particle (4) the part of the energy going to the recoil of the nucleus is generally quite small.
alpha decay