How is the nuclear structure of an atom similar to the non-nuclear structure?

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

What diagram shows the ionic compound of magnesium oxide

According to periodic trend, which of the following most likely has the highest ionization energy? kr be ni sc