Why alpha and beta decay will change the nucleus and produce new element?

Answer 1

Alpha radiation is when the nucleus of an unstable element releases an alpha particle (two protons and two neutrons; the equivalent of the nucleus of a helium atom)due to the weak nuclear force. The resulting atom is now a different element because the number of protons it has determines which element it is. Beta radiation (β− ) is when a neutron in an unstable atom with an excess of neutrons turns into a proton because of a virtual W− boson, one of the particles that carries the weak force. This boson then decays into an electron and an electron type antineutrino. Another type of beta radiation (β+ ) is the same as the previous type except that a proton decays into a neutron and a W+ boson decays into a positron (electron antiparticle) and an electron type neutrino instead. Beta radiation changes the number of protons in a nucleus and therefore the type of element.

Answer 2

Beta minus decay is the process in which a neutron transforms into a proton due to the weak interaction between the two. Because of conservation of charge also a negative charged element must be created. The reaction looks now like

neutron--> proton + electron

But also lepton number should be conserved, thus additionally a neutrino is emitted.

neutron--> proton + electron + neutrino.

This means that the Z value of the original element increases and becomes Z+1. Both the electron and the neutrino are emitted as "new" particles.

Something analog happens for beta plus.

In the case of alpha decay a helium nuclei is emitted from the nucleus of the decaying atom. A helium nuclei consists of 2 protons and 2 neutrons, hence the atom number of the initial nuclei decreases and the reaction looks as follows (Z,N) --> (Z-2, N -2) + He(Z=2, N =2) ( with Z the number of protons and N the number of neutrons) . This is only energetically favorable in heavy nuclei and occurs only then.