Democritus

(460 BC- 370 BC)

Through his many travels he picked extensive knowledge and was also said to be educated by Chaldean magi.

Democritus said that all matter was made up of small particles, which he named "atomos", and could not be broken down. These atoms were infinite, always moving, and could bind with each other.

Aristotle

                                      

384 BC- 322 BC

He was educated at Plato's academy.

Aristotle believed that all matter was created from air, water, fire, and earth. He also thought that matter could always be cut into smaller pieces.

John Dalton

September 6, 1766-  July 27, 1844


He was educated at a Quaker school.

Dalton re-introduced the idea of atoms. He added that each element was created from different types of atoms with unique masses and properties. He also proposed that compounds were formed with two or more different kinds of atoms.

Antoine Lavoisier

 August 26,1743- May 8, 1794

Lavoisier earned his law degree from College Mazarin but turned away from law to study math and science under prominent scientists of the time. His work in geology allowed him to later be accepted into the Academy of Sciences.

Lavoisier practiced excellent experimental skills which aided him in the discovery of the Law of the Conservation of Mass. He also named oxygen and hydrogen. Lavoisier went on to create a list of elements and develop the system on chemical nomenclature still used today. He is known as the "father of modern chemistry".

Fun fact: He was beheaded during the French Revolution.

William Crookes

June 17, 1832- April 4, 1919

Crookes was educated at the Royal College of Chemistry.

He discovered the element Thallium. Crookes also developed cathode-ray tubes and found that they are negatively charged.

JJ Thomson

December 18, 1856- August 30, 1940

Thompson was educated at Owens College, Manchester and Trinity College, Cambridge.

Thompson discovered the electron using cathode ray tube.
He proposed the Plum pudding Model.
He won the Nobel Prize in Physics in 1906

Thomson's Plum Pudding Model

Robert Millikan

March 22 1868- December 19, 1953

Millikan was educated at Columbia University and Oberlin College and received both his mastership in physics and his Ph.D. 

Using an oil-drop experiment, he calculated the charge of an electron, which allowed for the calculation of the mass of the electron.

He won the Nobel Prize in Physics in 1923.