John Dalton

Events

Democritus

332 BCE

A Greek philosopher who formulated an atomic theory for the cosmos. Often mentioned in correlation to his mentor Leucippus. He hypothesized that everything in the world consists of particles called atoms. he believed these atoms are indestructible, indivisible, and always in motion. All atoms are infinite in numbers, and come in different sizes and shapes.

Antonie Lavoisier

1785

he explained combustion and proposed the law of conservation of mass, which was the bases for Dalton's work. His started the conversation of what an atom really was

Josheph Proust

1794

Proust stated the Law of Definite Proportions which set up Dalton's theory

John Dalton

1803

His theory had four parts to it and he was the first to ever come up with the atomic theory. He created the bases for the modern day atomic theory. We still uses parts of his theory today. He believed that atoms were invisible particles we couldn't see.

Dmitri Mendeleev

1869

Referred to as the father of the modern periodic table. He created the periodic table and organized to the way it is now.

JJ Thomson

1897

Thomson was able to test the polarity of atoms and found almost all particles were negative or beta particles. He came up with the idea that toms were like plum pudding.

Ernest Rutherford

1911 - 1917

He came to the conclusion alpha particles are positive, beta particles are negative, and neutral a neutral particle is light.

Neils Bohr

1922

Bohr suggested that electrons didn't spiral into the nucleus but orbited into different levels. more energy let off=closer to the nucleus. absorbed=further away

Erwin Schrodinger

1926

Developed the electron cloud model of an atom.

James Chadwick

1932

Showed that a nucleus contains neutrons too.