The History of an Atom

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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.

Egypt

460 B.C.

Egypt revolts against Persian rule.

Roman

460 B.C.

Conflicts arise between the Roman patricians and plebians.

Fire

1803

Great fire in Bombay, India.

Ohio

1803

Ohio becomes the 17th state.

Dalton

1803

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

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.

Slaves

1808

Congress prohibits importation of slaves.

Coal

1808

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

J.J. Thomson

1897

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

British Bus

1897

1st British bus service opens.

Car Dealer

1897

World's 1st car dealer opens in London.

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.

Hawaii

1900

Hawaii became a US territory.

Eclipse

1900

Solar eclipse occurs.

Nagaoka

1904

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

Olympic Games

1904

Third modern Olympic Games opens in St. Louis.

Airplane flight

1904

First airplane flight lasts more than five minutes.

Millikan

1910

Provided a value for the eletronic charge.

Immigration

1910

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

Portugal

1910

Portugal becomes a repubic.

Rutherford

1911

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

Airplane Photo

1911

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

Elevator

1911

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

Bohr

1913

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

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.

Soviet

1923

Union of Socialist Soviet Republics is established.

Disney

1923

Disney company is founded.

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.

National Geographic

1926

National Geographic takes 1st natural-color undersea photos.

Chadwick

1932

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

World War 2

1932

World War 2: Japan occupies Harbin, China.

US Federal

1932

US federal gas tax enacted.