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Chapter 1

Note: |

The radius of a proton is approximately 10^{-15} meters, which gives it a volume of:
4π(R^{3})/3 = 4.19x10^{-30} m^{3}.

The radius of the electron's orbit around the proton is approximately
5.29 x 10^{-11} meters, which defines the radius of the atom. So the entire volume of the atom is about

4π(R^{3})/3 = 1.17x10^{-20}m^{3}.

(1.17x10^{-20} m^{3}) / (4.19x10^{-30} m^{3}) = 2.80x10^{9}.

The atom is 2.80x10^{9}, or 2,800,000,000, times larger than its nucleus; the volume of the electron is negligible. There's a number that gives you an appreciation for how empty an atom actually is! It's about the same as the ratio of the volume of a pea to that of a large, two-story house.