👉 The term "uridine" is a chemical element that has the symbol U and atomic number 8. It is one of the 7 naturally occurring bases in the cell, alongside carbon dioxide, nitrogen, oxygen, phosphorus, sulfur, and potassium. Uranium (U) is a type of radioactive isotope of uranium, which is also known as thorium-234. Uranium is a rare element with many important applications in nuclear energy, medicine, and materials science.