Question

Because the masses of subatomic particles are so small, a new unit, called what, was defined?

Answer 1

atomic mass unit

Chadwicks work resulted in a new understanding of the nucleus of the atom; it is comprised of both protons and neutrons. Because the masses of subatomic particles are so small, a new unit, called an atomic mass unit  amu , was defined. Protons and neutrons each have a mass of approximately one amu. The Table below describes the characteristics of the three subatomic particles we have discussed.