Atomic Model : Teague

Democritus

Oct 31, 1000

Lived in 500 B.C , and believed that all matter consisted of extremely small particles that can't be divided. He called the particles "atoms", and thought there were all different kinds of atoms with specific sets of properties.

Aristotle

Oct 31, 1000

Lived in 500 B.C., and he believed that there was no limit to the number of times matter could be divided. He usd a model to describe matter, because he thought all substances were built up from four elements (Fire, Earth, Water, Air)

John Dalton

Oct 31, 1766

Created a theory that said that all matter is made of individual particles called atoms, which cannot be divided.
He measured masses of elements that combine when a compound is formed.

Joseph Thomson

Oct 31, 1856

He did experiments that proved that atoms are made of even smaller particles called electrons. His experiments dealt with an electric current.

Ernest Rutherford

Oct 31, 1871

Discovered that uranium emits fast-moving particles that have a positive charge. He did an experiment to to find out what happens to alpha particles when they pass through a thin sheet of gold.

James Clerk Maxwell

Nov 1, 1873

Believed that electric & magnetic fields filled the space between the outside of the atom & the nucleus.

Niels Bohr

Oct 31, 1885

In his model, electrons move with constant speed in fixed orbits around the nucleus.

Werner Heisenberg

Nov 1, 1901

1901-1976 :
Created Principle of Indeterminancy - you can not know both the position and velocity of a particle.

Hantaro Nagaoka

Oct 31, 1904

Believes that an atom has a central nucleus and that electrons move in orbit & made a model to show it.

Ernest Marsden

Oct 31, 1911

Stated that an atom has a dense, positively charged nucleus & that electrons move randomly in the space around the nucleus. He created an experiment that made a beam pass through gold foil. He worked on this experiment with his teacher, Ernest Rutherford.

Louis de Broglie

Oct 31, 1924

Said that moving particles have some properties of waves. He collected evidence to show tbis.

Erwin Schrodinger

Oct 31, 1926

Developed mathematical equations to describe the motion of electrons in atoms. After all his work, he made an electon cloud model.

James Chadwick

Oct 31, 1932

Believed that atomic nucei contain neutrons and positively charged protons. He confirmed the existence of neutrons.