Question

There are three particles in the atom: protons, electrons, and neutrons, and none of these particles contribute to the atomic mass, so what is this particle?

Answer 1

Protons contribute to atomic number

Answer 2

Protons and neutrons are indeed responsible for most of an atom's mass, with each having a mass of about 1 atomic mass unit (amu). The mass of an electron is approximately 1/2000th of a proton or neutron, making its contribution to atomic mass negligible.

Step-by-step explanation:

Contrary to the student's statement, protons and neutrons do indeed contribute to the atomic mass. Atoms are comprised of protons, neutrons, and electrons, with protons and neutrons located in the nucleus. Protons have a positive charge, while neutrons are neutral—having no charge. Both protons and neutrons have approximately the same mass, which is around 1 atomic mass unit (amu). On the other hand, electrons are found orbiting the nucleus and have a negative charge. The mass of an electron is much smaller—about 1/2000 that of a proton or neutron, which is roughly equivalent to 0.0005 amu—so its contribution to the atomic mass is negligible.

In the terms of quantifying atomic mass, protons and neutrons are almost entirely responsible, given their significant mass relative to electrons. This mass is measured in atomic mass units, a scale which simplifies the comparison of atom and particle masses based on carbon as a standard. As such, in an atom's mass, the nucleus, which contains protons and neutrons, is the primary contributor. An electron's contribution to this mass is virtually non-existent in comparison.