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 its isotopes are unstable (with half-lives of the six naturally known isotopes, uranium-233 to uranium-238, varying between 69 years and 4.5 billion years). The most common isotopes of uranium are uranium-238 (which has 146 neutrons and accounts for almost 99.3% of the uranium found in nature) and uranium-235 (which has 143 neutrons, accounting for 0.7% of the element found naturally). Uranium has the second highest atomic weight of the primordially occurring elements, lighter only than plutonium. Its density is about 70% higher than that of lead, but 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.
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 its isotopes are unstable ( with half - lives of the six naturally known isotopes , uranium-233 to uranium-238 , varying between 69 years and 4.5 billion years ) . The most common isotopes of uranium are uranium-238 ( which has 146 neutrons and accounts for almost 99.3 % of the uranium found in nature ) and uranium-235 ( which has 143 neutrons , accounting for 0.7 % of the element found naturally ) . Uranium has the second highest atomic weight of the primordially occurring elements , lighter only than plutonium . Its density is about 70 % higher than that of lead , but 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 .
What is the atomic number of uranium?
What is the atomic number of uranium ?
92
92