Summarizing Discovery of the Atom

Discovery of the Atom Summary

• Atoms are the smallest unit of elements; atoms combine to form molecules, the smallest unit of compounds.
• The first direct observation of atoms was in Brownian motion.
• Analysis of Brownian motion gave accurate sizes for atoms (\({\text{10}}^{\text{−10}}\phantom{\rule{0.25em}{0ex}}\text{m}\) on average) and a precise value for Avogadro’s number.

Glossary

atom

basic unit of matter, which consists of a central, positively charged nucleus surrounded by negatively charged electrons

Brownian motion

the continuous random movement of particles of matter suspended in a liquid or gas