History of Atomic Model

Democritus

200

He made the thought that in every object that had small particals . He called these particals atoms and he found many different types. He says that all particals are made individually created and cannot be separated. He just thought of his theroy.

Aristotle

200

Aristotle said there was no limit in which matter could be divided . Thought that all of matter was made of four elements. (Water, earth,wind, and fire) He made figures that shown what he thought.

John Dalton

Oct 31, 1803

He pictured atoms as little tiny indestuctable particals with no internal structure. His expeirment was he made wooden spheres to represent atoms of different elements. he also said all atoms of a given element are identical in mass and properties and A chemical reaction is a rearrangement of atoms. This is what got many people thinking about the atomic theroy.

G.J. Stonley

Oct 31, 1884

He proposed that electricity was made of discrete negative particals he called "electrons." Conducted electricty in three physical units. He was the first person to introduce the electron.

E. Goldstein

Nov 1, 1886

He found electrons have electrical and magnetic properties. He discovered several important properties of cathode rays, which contributed to their later found as the first subatomic particle. He hit canel rays up against tin foil to find this out.

Joseph Thomson

Oct 31, 1897

He discovers electrons in atoms and discovers nucleus. He pictures electrons embedded in a sphere of positive electric charge. He made these discoveries because he used a scaled tube with gases in it with an electric current going threw it.

Hantaro Nagoaka

Oct 31, 1904

Model was based around the thought that electrons revolve around the positevly charged center of an atom. In which negative charges orbit, His expeirment was a planotary model of his theory.

Ernest Marsden

Nov 1, 1908

he worked along side with Neils Bohr and they both came to the thought that the nucleus was charged in side the atom. He also found fast moving alpha particals. He found this imformation off the experiment by Hans Geiger.

Ernest Ruthford

Oct 31, 1911

He had the thought that all thr positive charge in an atomic nucleus was contained in a volume 1/100,000 the size of the atom. He scatterd alpha particals off the nucleus with gold foil.

Niels Bohr

Oct 31, 1913

He had the thought that electrons move in a spherical orbit at fixed distances from the nucleus. He figured this out by making planotary model of his therory.

Louis de Broglie

Oct 31, 1924

He proposes that movinng particals like electrons have some properties of waves.He used the work of Albert Einstien to figoure this out.

Erwin Schrodinger

Oct 31, 1926

His work lead to the theroy about the electron cloud model. To figure this out he made a mathmatical equation to explain the movement of particals.

James Chadwick

Oct 31, 1932

Confirms neutrons, which have no eletric charge. Atomic nucleus contains neutrons and positivly charged electrons.He find this out by using a sample of berrllwum and combined it with alpha particals.