Becquerel and the discovery of radioactivity: early concepts

It has been 100 years since Becquerel discovered radioactivity shortly after he learned of Roentgens discovery of x-rays at a meeting of the French Academy of Science. His discovery in 1896 was a direct consequence of his work and that of his father and grandfather on phosphorescence and fluorescence. It resulted from the serendipitous use of uranium salts, which have known phosphorescent properties, to reproduce Roentgen rays with the mistaken notion that they were a related phenomenon. Intense investigation by Becquerel and others rapidly revealed the differences in these radiations and led to the discovery of beta, alpha, and gamma rays and the properties of radioactivity in numerous other substances. The work of Becquerel was acknowledged by Madame Curie to be the primary influence on the direction of her thesis toward the work that led to the isolation of radium and the introduction by her of the term radioactivity to describe these phenomena. Although the unit of radioactivity is now called the Becquerel in acknowledgement of his accomplishments, few people, even in the nuclear medicine field, are fully aware of the breadth and importance of his work. This article hopefully will help to resolve this.