Most of the particles went straight through the gold. It was like shooting a rifle into a thin line of trees. Some of the particles bounced off, some stuck inside, but the major portion of them passed through the gold foil. By Rutherford's calculations, the nucleus in an atom is like a BB in a boxcar. That is a genuinely outrageous idea. Almost all the mass of an atom is concentrated in the tiny nucleus. The mass of a proton or neutron is 1.66 E -24 grams or one AMU, atomic mass unit. The mass of an electron is 9.05 E -28 grams. This number is a billionth of a billionth of a billionth of a gram. It is not possible for