The Division of Adolescent Medicine provides primary and consultation services for adolescents and young adults between 12 and 21 years of age. We have a separate waiting room and examination area for these patients and offer services tailored to their needs and health care issues.
Modern atomic theory is generally said to begin with John Dalton, an English chemist and meteorologist who in 1808 published a book on the atmosphere and the behavior of gases that was entitled A New System of Chemical Philosophy.
Atom, from the Greek word atomos, which means indivisible, was first conceived around 2,400 years ago by a Greek man named Democritus. An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are very small; typical sizes are around 100 picometers (a ten-billionth of a meter, in the short scale).