Question

What two particles account for almost all of the mass of an atom?

Answer 1

`"Protons and neutrons..."`

Explanation:

The atom is composed of massive particles of formal positive, and neutral electronic charge, around which electrons, negatively-charged particles of negligible mass, whizz about. At nuclear ranges, which are MINUTE, the massive particles engage in the `"strong nuclear force"`, an attractive force which holds the nucleus together. The electronic charge signs of the electrons and the charged-nuclear particles are entirely arbitrary....the point is that that they oppositely charged...

Note that sometimes we refer to a `""^1H^+` particle as a `"proton"`. This is a bit of a misnomer even tho' it is technically true… because such protons are present in the nuclei of ALL elements. The number of protons determines `Z_"the atomic number.."`. How does the number of electrons relate to `Z`?