A hydrogen atom has a diameter of about 0.1 nm. If a hydrogen atom were to be magnified to the size of a one yen coin (approx. 20 mm in diameter), the original one yen coin magnified by the same extent would have a diameter of 4.5 times the Earth's. That's how small an atom is.

A hydrogen atom weighs 1.67 x 10-24 g, which means that there would be 23 zeros after the decimal point. That's how light a hydrogen atom is.

A little over a hundred different kinds of atoms have been discovered, and when atoms are combined, they create molecules. Ordinary-sized materials consist of an almost infinite number of atoms and molecules.

Nearly unimaginable smallness and quantities are the characteristics of atoms and molecules, the building blocks of matter.