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.
John Dalton pictures atoms as tiny, indestructible particles, with no internal structure.
Great fire in Bombay, India.
Ohio becomes the 17th state.
Anthracite coal is first burned as fuel, experimentally, in Wilkes-Barre, Pa.
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.
1st British bus service opens.
World's 1st car dealer opens in London.
J.J. Thomson, a British scientist, discovers the electron. He pictures electrons embedded in a sphere of positive electrical charges.
Solar eclipse occurs.
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.
First airplane flight lasts more than five minutes.
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.
US forbid immigration to criminals, anarchists, paupers, and the sick.
Provided a value for the eletronic charge.
Portugal becomes a repubic.
First photo in US taken from an airplane in San Diego.
First public elevator in London's Earl;s Court Metro Station.
Rutherford finds that an atom has a small, dense, positively charged nucleus. Electrons move around the nucleus.
In Bohr's model, the electron moves in aircular orbit at fixed distances from the nucleus.
The USA introduces income tax.
First US paved coast to coast highway, the Lincold highway is dedicated.
De Broglie proposes that moving particles like electrons have some properties of waves. Within a few years, experimental evidence suppports the idea.
Disney company is founded.
Union of Socialist Soviet Republics is established.
Lebanon adopts constitution.
National Geographic takes 1st natural-color undersea photos.
Erwin Schrodinger develops mathematical equations to describe the motion of electrons in atoms. His work leads to the electron cloud model.
James Chadwick, an English physicist, confirms the existence of neutrons, which have no charge. Atomic nuclei contain neutrons and positively charged protons.