old dudes time line

B.C. Early Greek models - Aristotle

350

350 B.C -Aristotle modified an earlier theory that matter was made of four “elements”: earth, fire, water, air. Aristotle was wrong. However, his theory persisted for 2000 years.

B.C - Democritus and the theory of an atom

400

Democritus was an Ancient Greek philosopher born in Abdera, Thrace, Greece. He was an influential pre-Socratic philosopher. Democritus thought matter could not be divided indefinitely.This led to the idea of atoms in a void. Democritus advanced the hypothesis that all matter was made up ultimately of microscopic, indivisible particles called atoms and that when you cut something, you were merely finding the spaces between the atoms.

Medieval Alchemy

Period: Apr 14, 1100 to Nov 27, 1300

At the heart of medieval alchemy was the idea that all matter was composed of four elements: earth, air, fire and water. With the right combination of elements, it was theorized, any substance on earth might be formed. •Medieval alchemists produced hydrochloric acid, nitric acid, potash and sodium carbonate.
•They were able to identify the elements arsenic, antimony, and bismuth.
• Medieval alchemists invented and developed laboratory devices and procedures.

Alburtus Magnus 1193 - 1280

Feb 28, 1248

He is credited with the discovery of the element arsenic[6]

John Dalton

May 9, 1794

Dalton's life discoveries He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness. Hcknowledged the "Atomic Theory of Matter", and the "Law of Multiple Proportions", and created the "Table of Atomic Masses".

Henri Becquerel

Feb 7, 1896

It is now known that Becquerel discovered one type of radioactivity – beta particles (beta-ray activity),

J.J Thomson

Mar 7, 1897

discovered the electron

Marie and Pierre Curie

Dec 28, 1898

they both doscovered Polonium and Radium (December 28 1898) if this link doesnt work type in on google marie and piere Curie timeline :) Marie and Piere Curie Timeline

Ernest Rutherford

Mar 7, 1911

At McGill Rutherford promptly discovered radon, a chemically unreactive but radioactive gas.
In 1898 Rutherford discovered that two quite separate types of emissions came from radioactive atoms and he named them alpha and beta rays. Beta rays were soon shown to be high speed electrons.
In 1908 he was awarded the Nobel Prize in Chemistry

Niels Bhor

Nov 10, 1913

created a detailed diagram of the structire of an electron contributing Ernehst Rutherfords ideas.

James Chadwick

Aug 15, 1932

Able to disintergrate the atom! 1919
Proved the existence of neutrons 1932!!!!!! Biography of James Chadwick