You are mostly made of empty space
If you removed all the empty space from the atoms making up every human on Earth, the entire global population could fit inside a single sugar cube. Atoms are 99.9999999 percent empty space. If the nucleus of an atom were the size of a marble, the electrons orbiting it would be about the size of dust motes located over half a mile away.
The Anatomy of an Atom
Every physical object in the everyday world, from the air we breathe to the cells making up our organs, is constructed from fundamental building blocks called atoms. An atom consists of a compact central nucleus surrounded by a cloud of one or more negatively charged electrons. The nucleus itself is composed of one or more positively charged protons and, in nearly all elements, electrically neutral particles known as neutrons. Protons and neutrons are collectively termed nucleons, and they are bound together tightly by the strong nuclear force, one of the fundamental forces of nature.
What makes the architecture of the atom remarkable is the extreme disparity between where its mass is stored and where its volume is established. Protons and neutrons are roughly eighteen hundred times more massive than electrons. Consequently, more than 99.9 percent of an atom's total mass resides inside the tiny nucleus. Yet, the spatial boundary of the atom is defined not by the nucleus, but by the outer perimeter of the electron cloud, which extends across a diameter tens of thousands of times larger than the nucleus itself.
Because the vast majority of an atom's physical volume contains only low-mass electrons moving through electric and quantum fields, ordinary matter is predominantly empty volume. If an atom were magnified to the scale of a vast sporting stadium, the nucleus at the center would be no larger than a small marble or a pea resting at midfield, while the outer boundaries established by the electrons would encompass the outer stands.
How the Nuclear Model Was Discovered
Before the early twentieth century, scientists understood that atoms existed, but their internal structure was a matter of active debate. Following the discovery of the electron by J. J. Thomson, the prevailing scientific consensus envisioned the atom as a diffuse sphere of positive charge embedded with negatively charged electrons, a concept known as the plum pudding model. In this framework, mass and electrical charge were thought to be distributed relatively uniformly throughout the entire volume of the atom.