NSCI 1322 Lecture Notes - Lecture 35: Technetium, Exponential Decay, Iodine-131
12 Jan 2017
School
Department
Course
Professor
Document Summary
Although technetium-99 is radioactive and decays by emitting beta particles (electrons), it is impossible to say when a particular nucleus will disintegrate. A sample of technetium-99 continues to give off beta rays for millions of years. Thus, a particular nucleus might disintegrate the next instant or several million years later. The rate of this radioactive decay cannot be changed by varying the temperature, the pressure, or the chemical environment of the technetium nucleus. Radioactivity, whether from technetium or some other nucleus, is not affected by the variables that affect the rate of a chemical reaction. The rate of radioactive decay that is, the number of nuclei disintegrating per unit time is found to be proportional to the number of radioactive nuclei in the sample. You can express this rate mathematically as rate = knt. K is the radioactive decay constant, or rate constant for radioactive decay.
