The History of an Atom

Main

Roman

460 B.C.

Conflicts arise between the Roman patricians and plebians.

Egypt

460 B.C.

Egypt revolts against Persian rule.

Democritus

460 B.C

Democritus discovered that all atoms are indvisible, exactly alike, and all matter is made up of atoms. Atoms cannot be destroyed only changed.

Ohio

1803

Ohio becomes the 17th state.

Fire

1803

Great fire in Bombay, India.

Dalton

1803

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

Slaves

1808

Congress prohibits importation of slaves.

Coal

1808

Anthracite coal is first burned as fuel, experimentally, in Wilkes-Barre, Pa.

Dalton

1808

According to Dalton, matter is made up of tiny particles called atoms. The atom is the smallest particle of matter that takes part in a chemical reaction. Atoms are indivisible and cannot be created or destroyed.

British Bus

1897

1st British bus service opens.

J.J. Thomson

1897

J.J. Thomson, a British scientist, discovers the electron. He pictures electrons embedded in a sphere of positive electrical charges.

Car Dealer

1897

World's 1st car dealer opens in London.

Hawaii

1900

Hawaii became a US territory.

Goldstein

1900

Goldstein said that atoms contain positively charged particles called protons. Since atoms contain negatively charged particles, they must contain positively charged particles for them to be electrically neutral.

Eclipse

1900

Solar eclipse occurs.

Airplane flight

1904

First airplane flight lasts more than five minutes.

Olympic Games

1904

Third modern Olympic Games opens in St. Louis.

Nagaoka

1904

Nagaoka suggests that an atom has a central nucleus. Electrons move in orbits like the rings around Saturn.

Portugal

1910

Portugal becomes a repubic.

Immigration

1910

US forbid immigration to criminals, anarchists, paupers, and the sick.

Millikan

1910

Provided a value for the eletronic charge.

Elevator

1911

First public elevator in London's Earl;s Court Metro Station.

Airplane Photo

1911

First photo in US taken from an airplane in San Diego.

Rutherford

1911

Rutherford finds that an atom has a small, dense, positively charged nucleus. Electrons move around the nucleus.

Paved Highway

1913

First US paved coast to coast highway, the Lincold highway is dedicated.

Income Tax

1913

The USA introduces income tax.

Bohr

1913

In Bohr's model, the electron moves in aircular orbit at fixed distances from the nucleus.

Disney

1923

Disney company is founded.

Soviet

1923

Union of Socialist Soviet Republics is established.

De Broglie

1923

De Broglie proposes that moving particles like electrons have some properties of waves. Within a few years, experimental evidence suppports the idea.

National Geographic

1926

National Geographic takes 1st natural-color undersea photos.

Schrodinger

1926

Erwin Schrodinger develops mathematical equations to describe the motion of electrons in atoms. His work leads to the electron cloud model.

Lebanon

1926

Lebanon adopts constitution.

US Federal

1932

US federal gas tax enacted.

World War 2

1932

World War 2: Japan occupies Harbin, China.

Chadwick

1932

James Chadwick, an English physicist, confirms the existence of neutrons, which have no charge. Atomic nuclei contain neutrons and positively charged protons.