Mass of all particles = 1 AMU (~1.6605e-18 Microgram)
- The SI unit known as the Atomic Mass Unit, abbreviated AMU, is used to express the masses of subatomic particles.
- Scientists assign each proton a mass of 1 AMU and symbol 'p.' All protons are identical, no matter from which kind of element they come.
- The AMU is used to express the relative masses of, and thereby differentiate between, various isotopes of elements.
- Thus, for example, uranium-235 (U-235) has an AMU of approximately 235, while uranium-238 (U-238) is slightly more massive.
- The difference results from the fact that U-238, the most abundant naturally occurring isotope of uranium, has three more neutrons than U-235, an isotope that has been used in nuclear reactors and atomic bombs.
[credit: study.com, techtarget.com]