Answer:
hen the number of neutrons is known and the atomic number of an element is known, it becomes easier to determine the approximate mass number by adding the two.
Explanation:
Hope it shelps
The puzzles about protons in the nucleus come from the Coulmb's interaction. We do know that particles of similar charges repel eachother. So how two (or more) protons (with positive charge) can be so close together in a nucleus?
One of the things that neutrons do is to be between neighbor protons, in some way, "reducing" that Coulomb's interaction between the protons.
There is also a puzzle (kinda still to this day) about the mass of a nucleus. Particularly because a given element could have different weights.
The different weights thing then can happen because these two atoms have a different number of neutrons in their nucleus (are two different isotopes of the same material). This is because all materials have a fixed number of protons and a "kinda" fixed number of electrons (they can gain or lose one for some time) but the number of neutrons is a little bit more free, so their existence explains how we can find two atoms of the same material with different weight.
If you want to learn more, you can read:
https://brainly.com/question/15916785
