Timeline

Question 1

Christopher Columbus Makes His First Voyage of Discovery to the Americas.

Answer 1

1492

Question 2

Robert Boyle publishes The Sceptical Chymist

Answer 2

1661

The book proposes that the true elements are substances such as sulfur and mercury-not earth, air, water, and fire.

Question 3

Antoine-Laurent Lavoisier Proposes the Law of Conservation of Mass.

Answer 3

1785

It states that mass is neither lost nor gained during a chemical reaction.

Question 4

Joseph-Louis Proust Proposes the Law of Definitive Proportions.

Answer 4

1794

Which states that the ratio of elements in a given chemical compound is constant.

Question 5

William Nicholson and Anthony Carlisle discover electrolysis.

Answer 5

1800

Question 6

John Dalton Publishes the first atomic theory.

Answer 6

1803

Question 7

Johann Heinrich Wilhelm Geissler invents cathode ray tubes.

Answer 7

1855

Question 8

James Clerk Maxwell develops four equations based on Michael Faradays work on electromagnetism.

Answer 8

1864

Question 9

Dmitry Ivanovich Mendeleyev proposes organizing all know elements into a periodic table of elements.

Answer 9

1870

Question 10

Wilhem Conrad Roentgen discovers X-Rats.

Answer 10

1895

Question 11

J.J. Thomson discovers the electron.

Answer 11

1897

Question 12

Lucretius writes On the Nature of Things, a poem reinstating concepts of atomism.

Answer 12

50 B.C.

Question 13

Greek Philosophers Leucippus and Democritus propose that all matter is formed from atoms.

Answer 13

400 B.C.

A philosophy known at atomism.

Question 14

Antoine-Henri Becquerel discovers radioactivity.

Answer 14

1898

Question 15

Pierre and Marie Curie announce their discovery of the radioactive elements polonium and radium.

Answer 15

1898

Question 16

Albert Einstein publishes his special theory of relativity, including E=MC2. In the same year, he also explains the photoelectric effect.

Answer 16

1905

Question 17

Earnest Rutherford discovers the proton and the atomic nucleus.

Answer 17

1909

Question 18

Neils Bohr proposes a new atomic model of hydrogen with mathematically defined “permitted orbits” for the electron.

Answer 18

1913

Question 19

Henry Moseley uses X-Ray diffraction to measure the amount of positive charge in atomic nuclei.

Answer 19

1913

The discovery lead to a reorganization of the periodic table of elements.

Question 20

World War I is fought

Answer 20

1914-1918

Question 21

Louis de Broglie proposes that all forms of matter exhibit both wave and particle characteristics.

Answer 21

1923