Final answer:
Protons and neutrons each have an approximate mass of 1 amu, where the proton's mass is 1.0073 amu and the neutron's mass is 1.0087 amu, which are considered essentially equivalent for most purposes in chemistry.
Step-by-step explanation:
The weight of protons and neutrons in atomic mass units (amu) is approximately the same, with a proton having a mass of about 1.0073 amu and a neutron having a mass of about 1.0087 amu. An atomic mass unit is defined as one-twelfth the mass of a carbon-12 atom, making it a very small unit of weight equal to 1.660539606660 × 10-27 kilograms. Since electrons are much lighter, having a mass of approximately 0.00055 amu, their contribution to an atom's overall atomic mass is quite minimal.