- The Curie was named after physicist Marie Curie. - It is defined as the activity of a quantity of radioactive material in which 3.7 × 10^10 disintegrations occur per second. This value is approximately the radioactivity of 1 gram of the radium isotope ^226Ra. - While still in use, the internationally recognized SI unit for radioactivity is the Becquerel (Bq), which is defined as one disintegration per second. - 1 Curie = 3.7 × 10^10 Becquerel.