Democritus first suggested the existence of the atom but it took almost two millennia before the atom was placed on a solid foothold as a fundamental chemical object by John Dalton (1766-1844). Although two centuries old, Dalton's atomic theory remains valid in modern chemical thought. 1) All matter is made of atoms.
A bust of Democritus (or Democrites), who came up with the idea of indivisible atoms. The earliest known proponent of anything resembling modern atomic theory was the ancient Greek thinker Democritus. He proposed the existence of indivisible atoms as a response to the arguments of Parmenides, and the paradoxes of Zeno.
- J. J. Thompson
- In the late 19th century with the discovery of the electron, and in the early 20th century, with the discovery of the atomic nucleus, and the birth of particle physics, matter was seen as made up of electrons, protons and neutrons interacting to form atoms.
- Democritus was a Greek philosopher (470-380 B.C.) who is the father of modern atomic thought. He proposed that matter could NOT be divided into smaller pieces forever. John Dalton created the very first atomic theory.
Democritus was a Greek philosopher (470-380 B.C.) who is the father of modern atomic thought. He proposed that matter could NOT be divided into smaller pieces forever. John Dalton created the very first atomic theory.
- Atoms were thought to be the smallest possible division of matter until 1897 when J.J. Thomson discovered the electron through his work on cathode rays. A Crookes tube is a sealed glass container in which two electrodes are separated by a vacuum.
- In 1911, Niels Bohr earned his PhD in Denmark with a dissertation on the electron theory of metals. Right afterwards, he went to England to study with J.J. Thomson, who had discovered the electron in 1897.
- The Plum Pudding Model is a model of atomic structure proposed by J.J. Thomson in the late 19th century. Thomson had discovered that atoms are composite objects, made of pieces with positive and negative charge, and that the negatively charged electrons within the atom were very small compared to the entire atom.
Updated: 3rd October 2019