The answer is; Jane would be right.
The atom was discovered be more of empty space. The mass of an atom is mainly attributed to the mass of the nucleus which occupies a very small fraction of the size of the atom. The nucleus is Located in the center surrounded by orbiting electrons.
The Geiger–Marsden experiment, where alpha particles are accelerated onto a thin aluminum foil proved this theory by Ernest Rutherford. Some of the particles were deflected by the foil and this was attributed to the dense nucleus of the aluminum atoms in the foil. The other particles passed through because most of the atoms are made of empty space.