It is called Mass.
Among the physical characteristics of a matter which includes Weight, Mass, Volume, and Density the only characteristic that does not change is the mass. The mass of an object never change from place to place. All the objects have a mass and that is why there is a weight but it changes depends on the gravity. Mass don't.
Answer:
The area around the nucleus must be of low mass.
Explanation:
Rutherford`s experiment showed that there are some positive charges in the center of the atoms, and because they are all together, they will give a great mass to the atom.
It was quite different from Thomson`s experiment, in which it was thought that the negative charges were mixed with the positive charges, around the atom (like a Pudding Model). In Rutherford`s experiment, because the direction of beta particles, it was the prediction of the positive nucleus.
Hope this info is useful.
This is the symbols for protons, neutrons, and electrons
