Democritus discovered that all atoms are indvisible, exactly alike, and all matter is made up of atoms. Atoms cannot be destroyed only changed.
Egypt revolts against Persian rule.
Conflicts arise between the Roman patricians and plebians.
Great fire in Bombay, India.
Ohio becomes the 17th state.
John Dalton pictures atoms as tiny, indestructible particles, with no internal structure.
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.
Congress prohibits importation of slaves.
Anthracite coal is first burned as fuel, experimentally, in Wilkes-Barre, Pa.
J.J. Thomson, a British scientist, discovers the electron. He pictures electrons embedded in a sphere of positive electrical charges.
1st British bus service opens.
World's 1st car dealer opens in London.
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 became a US territory.
Solar eclipse occurs.
Nagaoka suggests that an atom has a central nucleus. Electrons move in orbits like the rings around Saturn.
Third modern Olympic Games opens in St. Louis.
First airplane flight lasts more than five minutes.
Provided a value for the eletronic charge.
US forbid immigration to criminals, anarchists, paupers, and the sick.
Portugal becomes a repubic.
Rutherford finds that an atom has a small, dense, positively charged nucleus. Electrons move around the nucleus.
First photo in US taken from an airplane in San Diego.
First public elevator in London's Earl;s Court Metro Station.
In Bohr's model, the electron moves in aircular orbit at fixed distances from the nucleus.
First US paved coast to coast highway, the Lincold highway is dedicated.
The USA introduces income tax.
De Broglie proposes that moving particles like electrons have some properties of waves. Within a few years, experimental evidence suppports the idea.
Union of Socialist Soviet Republics is established.
Disney company is founded.
Erwin Schrodinger develops mathematical equations to describe the motion of electrons in atoms. His work leads to the electron cloud model.
Lebanon adopts constitution.
National Geographic takes 1st natural-color undersea photos.
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: Japan occupies Harbin, China.
US federal gas tax enacted.