Uranium has a high atomic weight because it has a relatively large number of protons, neutrons, and electrons compared to lighter elements. The atomic weight of an element is determined by the total number of protons and neutrons in its nucleus.
Uranium (symbol: U) has an atomic number of 92, which means it has 92 protons in its nucleus. The atomic number determines the element's identity and its position on the periodic table. Uranium is a naturally occurring element that can be found in small amounts in the Earth's crust.
Most uranium isotopes also have a significant number of neutrons in their nuclei. The most abundant naturally occurring isotope of uranium, uranium-238, has 146 neutrons. Other isotopes of uranium, such as uranium-235 and uranium-234, have slightly different neutron numbers.
The combination of a large number of protons and neutrons in the nucleus of uranium contributes to its high atomic weight. It is worth noting that atomic weight is a weighted average of the masses of all the naturally occurring isotopes of an element, taking into account their relative abundance.