On this day 100 years ago, Frederick Soddy used the term isotope for the first time.

In his published paper he wrote:

“The same algebraic sum of the positive and negative charges in the nucleus, when the arithmetical sum is different, gives what I call "isotopes" or "isotopic elements," because they occupy the same place in the periodic table.”  
– F. Soddy, Nature 92 (1913) 399, December 4, 1913

From that day forward, numerous advances have been made in nuclear science and the study of isotopes, leading up to the present day national user facilities and laboratories world-wide with practitioners dedicated to the research and discovery of these isotopes.

In honor of this, December 4 will be recognized at FRIB as ‘Isotope Day.’ For more information about Isotope Day and the work of Frederick Soddy, visit the website of the University of Glasgow.