What is the name of an atoms inner region?

Answer 1

The centre of an atom is the nucleus (made up of the protons and the neutrons). The nucleus is very small. It occupies only a tiny fraction of the atom volume. It has A positive charges, where A is the atomic number.

The electrons make up the rest of the volume of the atom. They are arranged in shells, like an onion, according to the principle quantum number and its sub-numbers. There will be A negative electrons in a neutral atom where A is the atomic number.

The innermost shell (lowest principle quantum number) is called 1 in modern practice, K from earlier practice. Both the 1,2,3,4,5,6,7... numbering and K,L,M,N,O,P,Q,... are in current use.

The innermost shell, K or 1, holds only 2 electrons maximum. The second shell is referred to as L or 2 and it holds 8 electrons maximum. The third shell labelled M or 3, holds 18 electrons maximum, but here we run into a problem. Because of energy consideration, there will be no more than 8 electrons in 3 or in any other outer (valence) shell. Once the third shell has hit 8 electrons, the next electrons must go into shell 4. Then, since 4 is now the outer shell, more electrons can be placed into shell 3 taking it to 18.

Answer 2

The inner region of an atom is called the nucleus. It contains protons and neutrons, which make up the majority of an atom's mass.

Answer 3

it is called nucleus

Answer 4

proton