History of an Atom Timeline

People

Democritus

440 B.C

Democritus was first to suggest exsistence of atoms. He believed atoms were indestructible and indivisible.

John Dalton

1803

John Dalton pictures atoms as tiny indestructible particles, with no internal structure.

John Dalton

1803

Dalton's Atomic Theory.

Eugen Goldstein

1886

Observed a cathode ray tube and found rays traveling in the direction opposite of the cathode ray. This was evidence for a positively charged particle called a proton.

J.J Thomson

1897

Discovered the electron. This later leads to his "plum-pudding" model. He pictures electrons embedded in a sphere of positive electrical charge.

Hantaro Nagaoka

1904

Suggests that an atom has a central nucleus and that electrons move in orbit.

Ernest Rutherford

1911

Atoms have a small, dense, positively charged nucleus with electrons moving around it.

Niels Bohr

1913

Believed the electron moves in a circular orbit at fixed distances from the nucleus.

Robert A. Millikan

1916

Did experiments to find quantity of charge carried by an electron. He ended up calculating the mass of an electron.

Louis De Broglie

1923

Proposes that moving particles like electrons have some properties of waves. After a few years experimental evidence supported this idea.

Erwin Schrodinger

1926

Developed mathematical equations to describe the motion of electrons in atoms, leading to the electron cloud model.

James Chadwick

1932

Confirms the existence of neutrons, which have no charge.

History

440 B.C

440 B.C

Battle of Samos. Greek city states made peace with the Persian Empire.

1803 History

1803

Meteorites fall in L'Aigle France. First horses arrive in Hawaii.

1803 History

1803

Great fire in Bombay, India. Ohio becomes the end of the state

1886 History

1886

Slavery abolished in Cuba. China takes over Burma.

1897 History

1897

Japan adopts Gold Standard. World's first car dealer opens in London.

1904 History

1904

Russian-Japanese War begins. First airplane flight to last more than five minutes.

1911 History

1911

First International Women's Day. South Pole first reached by Norwegian Roald Amundson.

1913 HIstory

1913

First drive up gasoline station opens. Greece formally takes possession of Crete.

1916 History

1916

US Senate agrees to participate in World War 1. Bulgaria declares war on Romania.

1923 History

1923

Draft Law passes. Time Magazine debuts.

1926 History

1926

Italian-Spanish peace treaty signed. Germany joins League of Nations.

1932 History

1932

Japan and China sign a peace treaty. Japanese forces attack and occupy Shanghai.