☢️ Uranium vs Radium: Which One Is More Radioactive? Uranium and radium are both radioactive elements, but their radioactivity is very different. The key difference comes down to half-life, decay rate, and how many radioactive atoms are present in a given amount. 🧪 Uranium is a naturally occurring radioactive metal. The most common isotope, uranium-238, has an enormous half-life of about 4.5 billion years. That means it decays extremely slowly. Even though uranium contains a huge number of radioactive atoms, only a tiny fraction decay at any given moment. ⚛️ Radium, on the other hand, is much more intensely radioactive. Radium-226 has a half-life of about 1,600 years, meaning its atoms decay much more rapidly than uranium-238. As a result, a gram of radium can produce vastly more radioactive decays per second than a gram of uranium. That doesn't mean radium is simply “more dangerous” in every possible situation. Radioactivity depends on the isotope, amount, type of radiation, expo...