Count the protons within the atom. This will depend upon which element's atom you have chosen to scale. The atomic number of the element is equal to the number of protons in the atom's nucleus, so the element Helium, with its atomic number of two, has two positively charged protons.
Count the electrons within the atom. As each element has an overall neutral charge, these two positively charged particles must be counteracted by an equal number of negatively charged particles. Therefore, Helium has two of these particles, known as electrons.
Count the neutrons within the atom. Because the mass of an electron is so miniscule that it is considered negligible, the remainder of the mass of the atom is made up of neutrally charged particles called neutrons. The Helium atom has an atomic weight of four. This figure, minus the atom's two protons, gives Helium a total of two neutrons. Only Hydrogen, with its atomic mass of one, has no neutrons.
Draw the basic structure of the atom. The protons and neutrons of the atom are packed tightly together in its nucleus, while the electrons orbit the positively charged nucleus in shells. The first shell accommodates two electrons, the second holds eight and the third holds 18. The structure of a Helium atom consists of a tightly packed nucleus of two protons and two neutrons, and one complete shell of two electrons. Technetium, a more complicated atom, will have a nucleus of 43 protons and 55 neutrons, orbited by five shells of electrons, including an incomplete outer shell with just one electron.
Scale the particles up. This is difficult because scientists cannot yet agree on an exact measurement for the diameter of an electron. The Classical Electron Radius of 2.8179402893(58) x 10 to the power of -15 m refers to the radius of the electron's magnetic field and not its actual radius. For the purposes of representation, scientists define the diameter of an electron as being 1,000 times smaller than that of a proton, which is roughly the same as that of a neutron. So, if you scale up your proton particle to five inches across, your electron particle will be 0.005 inches in diameter.
Scale the structure up. For representational purposes, scientists have measured the diameter of a Hydrogen atom as being 1,000 times greater than that of a proton. Helium atoms are 1.28 times larger than Hydrogen atoms, so, with a proton diameter of 5 inches, the distance from the center of the nucleus to the outer edge of the electron shell would be 266.67 feet.