That was the line up or the nuclear material so the fission or the implosion could yield a colossal release of energy.
Albert Einstein
j.robert oppenheimer
I believe you are referring to Albert Einstein.
Robert Oppenheimer and his team of scientists.
he practically discovered the neutron which then some scientist came out with something called fission
The scientist that designed the atomic theory is Thomas Jefferson.
Dmitri Mendeleev was the scientist who arranged the periodic table according to the element's Atomic Mass. Later on, he then arranged it according to the element's Atomic Number.
Henry Moseley is the scientist who discovered that the atomic number rather than the atomic weight is more responsible for the properties of an element.
They didn't help with atomic theory, they created it.
The Atomic Theory
Leo Szilard.
mitchell creech
Rutherford
Henry Moseley
Einstein was an atomic scientist inasmuch as he advanced the field of atom theory. His paper on "Brownian Motion" was one of the first to describe the free flowing motion of atoms in space. This question suffers from a question of intent. The short and long of it is yes, Einstein was a research theorthetical atomic scientist.
Robert Oppenheimer.
John Dalton