As you know, an atom is formed by the electrosphere (where the electrons are) and the nucleus (where the neutrons and protons are).
The nucleus is a very small region in the atom and although it occupies less space than the electrosphere, it contains practically the entire atomic mass, for this reason it is the densest region of the atom. This is because the entire mass of an atom corresponds to the sum of all its protons and the protons are in the nucleus.
The nucleus accounts for nearly all mass in an atom. It is positively charged. It is made up of protons and neutrons. The electron cloud surrounding the nucleus is 100,000 times the size of the nucleus.
