when a radioactive atom emits an alpha particle the original atom's mass number decreases by 6. 1 mev.
when a radioactive atom emits an alpha particle the original atom's mass number decreases by 6. 1 mev.
when a radioactive atom emits an alpha particle the original atom's mass number decreases by?
6. 1 mev
the best-known source of alpha particles is alpha decay of heavier ( 106 u atomic weight) atoms. when an atom emits an alpha particle in alpha decay, the atom's mass number decreases by four due to the loss of the four nucleons in the alpha particle. the atomic number of the atom goes down by exactly two, as a result of the loss of two protons – the atom becomes a new element. examples of this sort of nuclear transmutation are when uranium becomes thorium, or radium becomes radon gas, due to alpha decay.
alpha particle
different types of radioactive decay are characterized by their changes in mass number as well as atomic number, according to the radioactive displacement law of fajans and soddy. 









































for example, uranium-238 usually decays by alpha decay, where the nucleus loses two neutrons and two protons in the form of an alpha particle. thus the atomic number and the number of neutrons each decrease by 2 ("z": 92→90, "n": 146→144), so that the mass number decreases by 4 ("a" = 238→234); the result is an atom of thorium-234 and an alpha particle ():
mass number