discovery of radioactivity in 1986 introduced a new era in the development
of modern physics- one known today as nuclear physics. In the original discovery,
the radioactive rays emanated from uranium ( Z = 92), gave rise to the question
of whether radioactivity is a property of uranium only or of the so called
heavy elements with high atomic numbers. The former supposition was disapproved
by the discovery, soon afterwards, of other radioactive substances such as
thorium (Z = 90) and Radium (Z = 88). even certain salts of potassium and
of rubidium were found to be radioactive. Today we know that all the elements
with an atomic number of greater than 83
(Z = 83) are, to a degree, radioactive.
soon after the discovery of radiactivity, it was established that naturaly radioactive subatances give rise to three types or rays: Alpha rays, beta rays, and gamma rays.
There are other famous scientists such as Marie Curie.