The stable and non-radioactive elements can also be changed into radioactive elements .Such artificially produced radioactive elements are called radioactive isotopes.These are unstable isotopes of the elements which are undergoing nuclear transmutations by themselves and are emitting radiations.
These are some very important radioisotopes which are used in daily life.
These are manufactured mainly by irradiating substance with neutrons in a nuclear reactor but they can also be made by bombardment with high energy particles from an accelerator.
Gamma rays, which are unaffected by the electric field, must be uncharged. Because the loss of an α particle gives a daughter nuclide with a mass number four units smaller and an atomic number two units smaller than those of the parent nuclide, the daughter nuclide has a larger n:p ratio than the parent nuclide.
If the parent nuclide undergoing α decay lies below the band of stability (refer to Chapter 21.1 Nuclear Structure and Stability), the daughter nuclide will lie closer to the band.
During the beginning of the twentieth century, many radioactive substances were discovered, the properties of radiation were investigated and quantified, and a solid understanding of radiation and nuclear decay was developed.
The spontaneous change of an unstable nuclide into another is radioactive decay.
Following the somewhat serendipitous discovery of radioactivity by Becquerel, many prominent scientists began to investigate this new, intriguing phenomenon.
Among them were Marie Curie (the first woman to win a Nobel Prize, and the only person to win two Nobel Prizes in different sciences—chemistry and physics), who was the first to coin the term “radioactivity,” and Ernest Rutherford (of gold foil experiment fame), who investigated and named three of the most common types of radiation.
In general, most of the nuclei with atomic number 1 to 82 are stable nuclei.