History and Production The name is derived from radium. It was
discovered in 1900 by F.E. Dorn who called it radium emanation.
It was first isolated and studied in 1902 by E. Rutherford and
F. Soddy. In 1908, W. Ramsey has also isolated the element and
named it niton. He had determined the density and found it to be
the heaviest known gas. Other names has also been called,
depending on which radioactive series it originates in. Since
1923, it has been called radon. It is used in the treatment of
cancer and as a radioactive source in testing metal castings. It
is a colorless gas. When frozen, it exhibits a phosphorescence
which becomes yellow as the temperature is lowered. Radon is
present in minute amount (1 part of radon in 1 x 1021 part of
air) in the atmosphere due to the decay of natural radium.
Recently, radon is a health concern since its release from soils
can easily trapped indoors. Inhaling radon has result in deaths
from lung cancer due to the radioactive a emmission. Interatomic
distance: - Melting