<Tr> <Td_colspan="2"> <Ul> <Li> view </Li> <Li> talk </Li> <Li> </Li> </Ul> references in Wikidata </Td> </Tr> <Ul> <Li> view </Li> <Li> talk </Li> <Li> </Li> </Ul> <P> Uranium is a chemical element with symbol U and atomic number 92 . It is a silvery - white metal in the actinide series of the periodic table . A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons . Uranium is weakly radioactive because all isotopes of uranium are unstable, with half - lives varying between 159,200 years and 4.5 billion years . The most common isotopes in natural uranium are uranium - 238 (which has 146 neutrons and accounts for over 99%) and uranium - 235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements . Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten . It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium - bearing minerals such as uraninite . </P> <P> In nature, uranium is found as uranium - 238 (99.2739--99.2752%), uranium - 235 (0.7198--0.7202%), and a very small amount of uranium - 234 (0.0050--0.0059%). Uranium decays slowly by emitting an alpha particle . The half - life of uranium - 238 is about 4.47 billion years and that of uranium - 235 is 704 million years, making them useful in dating the age of the Earth . </P>

Where is uranium located on the periodic table