The size of an atom is typically measured in picometers (pm), where 1 picometer equals one trillionth of a meter (10^-12 meters). . The diameter of an average atom is about 0.1 nanometers (nm), or 100 picometers, though this can vary depending on the element. . For example, a hydrogen atom has a diameter of about 0.1 nm, while larger atoms like those of uranium can be around 0.3 nm in diameter. . Atoms are mostly empty space, with the nucleus being very small compared to the overall size of the