Radioactive disintegration series

Radioactivity is the phenomenon of emission as a result of the spontaneous disintegration of alpha-beta and gamma rays within the nucleus of an atom. Since radioactive disintegration is a continuous process hence a series can be drawn which is known as radioactive disintegration series. There are four such series:

Thorium series (4n series)

It begins with Thorium-232 and ends at Lead — 208 with the emission of six alpha and four beta rays.

Neptunium series (4n + 1 series)

It begins with Neptunium — 241 and ends at Bismuth — 209 with the emission of eight alpha rays and five beta particles.

Uranium-series (4n + 2 series)

Begins with Uranium — 238 and ends at Lead — 206 with the emission of eight alpha rays and six beta rays.

Actinium series (4n + 2 series)

It begins with Uranium — 235 and ends at radioactive isotopes of Lead — 208 with the emission of seven alpha rays and four beta rays.

When an Alpha particle ejected from within the nucleus the mother element loses two units of atomic number and four units of mass number.
Thus, if a radioactive element with mass number M and atomic number Z ejected an alpha particle the newborn chemical element has mass number = (M — 4) and atomic number = (Z — 2).

When a beta particle is emitted from the nucleus of an atom, the daughter element nucleus has an atomic number one unit greater than that of the mother element nucleus. Thus, if a radioactive element with mass number M and atomic number Z ejected a beta particle the newborn element has a mass number the same and atomic number = (Z + 1).

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