U is for Uranium
Uranium is known best for its radioactive isotopes. As scientists working with stable isotopes – and light ones at that – we regularly grapple with the misconception that anything called an “isotope” is radioactive and is a potential component of dirty bombs.
Uranium has many isotopes, all of which are radioactive, which means they are unstable and will spontaneously break down into other stable (not-radioactive) isotopes. The atomic number of uranium is 92, meaning that there are 92 protons int he nucleus. Most uranium in nature is urnaium-238 (92 protons + 146 neutrons), but there is also uranium-235 and uranium-234. Both uranium-238 and uranium-235 decay to form stable isotopes of lead (lead-206 and lead-207, respectively). By measuring the ratios of uranium to lead in these two systems, it is possible to determine ages of rocks that are millions to billions of years old.
Analysis of uranium isotopes is not done at SIREAL, as our instrument will not analyze materials with atomic numbers much higher than 20.