Who First Proposed Atomic Theory?


Vincent White

The concept of atomic theory has been around for centuries, but who first proposed it? Let’s take a deeper look into the origins of this fundamental scientific theory.

The Beginnings of Atomic Theory

The ancient Greeks were some of the first people to consider the idea that matter was made up of tiny particles. The philosopher Democritus, who lived in the 5th century BCE, was one of the earliest proponents of this concept. He called these tiny particles “atomos,” which means indivisible in Greek.

However, it wasn’t until the 19th century that scientists began to develop a more detailed understanding of atomic theory. One scientist, in particular, is credited with laying the foundation for our modern understanding of atoms.

John Dalton and Atomic Theory

In the early 1800s, English chemist John Dalton proposed a series of ideas about atoms that formed the basis for modern atomic theory. Among other things, he suggested that:

  • All matter is made up of tiny particles called atoms.
  • Each element is made up of unique atoms.
  • Atoms cannot be created or destroyed.
  • Chemical reactions involve rearranging atoms.

Dalton’s ideas were revolutionary at the time and helped pave the way for further scientific inquiry into atomic structure.

The Discovery of Subatomic Particles

As technology improved in the late 19th and early 20th centuries, scientists were able to probe deeper into the structure of atoms. They discovered that atoms were not actually indivisible but were made up of even smaller particles called subatomic particles.

One scientist who played a key role in this discovery was J.J. Thomson. In 1897, he used a cathode ray tube to demonstrate that atoms contained negatively charged particles that we now call electrons.


While Democritus may have been the first person to suggest that matter was made up of tiny particles, it was John Dalton who laid the groundwork for our modern understanding of atomic theory. His ideas, along with discoveries made by later scientists like J. Thomson, have helped us develop a more detailed picture of the fundamental building blocks of matter.


  • https://www.britannica.com/topic/atom-chemistry/The-history-of-atomic-theory
  • https://www.livescience.com/amp/atom-theory-john-dalton.html
  • https://www.nobelprize.org/educational/physics/quantised_energy/discovery-electron.html