The atomic weight of uranium, like any other element, is determined by the combined masses of its protons, neutrons, and electrons. In the case of uranium, its atomic weight primarily comes from the sum of its protons and neutrons.
Uranium has an atomic number of 92, which means it has 92 protons in its nucleus. The number of protons defines the element and its position in the periodic table. However, uranium exists in different isotopes, which have varying numbers of neutrons.
The most common isotope of uranium, uranium-238 (U-238), has 146 neutrons, giving it a total of 238 nucleons (protons + neutrons). Other isotopes of uranium, such as uranium-235 (U-235), have different numbers of neutrons, resulting in different atomic weights.
The atomic weight of uranium is calculated by taking the weighted average of the atomic masses of its isotopes, considering their abundance in nature. This is why the atomic weight of uranium is typically reported as approximately 238.03 atomic mass units (amu).
It's worth noting that the atomic weight listed on the periodic table or in scientific literature may be an average value because it considers the different isotopes and their relative abundance.