Atomic Thoery Timeline

Demoticrus

300

Demotricus was an Ancient Greek philosopher born in Abdera, Thrace, Greece. A pupil of Leucippus, he was an influential pre-Socratic philosopher who formulated an atomic theory for the universe.

Antoine Lavoisier

Oct 31, 1779

Anoitne Lavoisier was a French nobleman and chemist central to the 18th-century. He is most noted for his discovery that oxygen plays a major role in combustion. He recognized and named oxygen and hydrogen and opposed the phlogiston theory. He also helped construct the metric system.

Law of Conservation of Mass

Oct 31, 1789

The Law of Conservation of Mass says that matter is neither created nor destroyed, but rather turned into a different form.

Dalton's Atomic Theory

Oct 31, 1803

Dalton's Atomic Thoery was composed of the following laws.
1) All matter is made of atoms. Atoms are indivisible and indestructible.
2) All atoms of a given element are identical in mass and properties
3) Compounds are formed by a combination of two or more different kinds of atoms.
4) A chemical reaction is a rearrangement of atoms.

John Dalton

Oct 31, 1803

John Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness. Blindness is actually sometimes refered to as Daltonism in his honor.

Dmitri Mendeleev

Oct 31, 1869

Dmitri Mendeleev was a Russian chemist and inventor. He formulated the Periodic Law, created his own version of the periodic table of elements, and used it to correct the properties of some already discovered elements and also to predict the properties of elements yet to be discovered.

Cathode Ray Tube

Oct 30, 1879

The cathode ray tube (CRT) is a vacuum tube containing one or more electron guns (a source of electrons or electron emitter) and a fluorescent screen used to view images.[1] It has a means to accelerate and deflect the electron beam(s) onto the screen to create the images. These were used in old computer monitors and telivisions to project the image onto the screen.

Plum Pudding Atomic Model

Oct 30, 1897

The plum pudding model of the atom by J. J. Thomson, who discovered the electron in 1897, was proposed in 1904 before the discovery of the atomic nucleus in order to add the electron to the atomic model. In this model, the atom is composed of electrons surrounded by a soup of positive charge to balance the electrons' negative charges, like negatively charged "plums" surrounded by positively charged "pudding".

JJ Thomson

Oct 30, 1897

Sir Joseph John Thomson was a British physicist. In 1897, Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, and thus is credited with the discovery and identification of the electron. Thomson is also credited with finding the first evidence for isotopes of a stable (non-radioactive) element in 1913 as part of his exploration into the composition of canal rays (positive ions) and with the invention of the mass spectrometer.

Robert Millikan

Oct 30, 1909

Robert Millikan was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for his measurement of the elementary electronic charge and for his work on the photoelectric effect.

Rutherford Model

Oct 31, 1911

Earnest Rutherford was born August 30, 1879, he was known as the Father of Phisics. He created his model based off of J. J. Thompsons pulm pudding model, but made some modifications to it. What his model describes that atmos have heavy nucleuses.

Henry Moseley

Oct 31, 1913

Born November 23, 1887 was an English Physics. He came up with the concept of atomic number and Mosely's Law. By sorting elements on the periodic table in an order based on their physics.

Neils Bohr

Oct 31, 1922

Born October 7, 1855 was a Danish physists who contributed to a better understnding of an atom and the quantum theory. He developed the Bohy Planetary concept. That electrons orbit around a nucleus as ifa planet would to the sun.

Gold Foil Experiment

Oct 31, 1926

Was an experiment that they had bombarded a tihin gold foil with alpha particles (positive charge) almost all particles passed through the foil.

Erwin Schrodinger

Oct 31, 1926

Born August 12, 1887 was an Australian physists who developed the Quantum Mechanical Model.

Quantum Mechanical Model

Oct 31, 1926

A model that explains how electrons exist in atoms and how those electrons determine the chemical and physical properties of elements.

Ernest Rutherford

Oct 31, 1926

Born August 30, 1871 was a New Zealand chemist and physists. Discovery of the nucleus proposed "Nuclear" model. Conducted the "Gold Foil Experiment".

James Chadwick

Oct 31, 1932

Born October 20, 1891 in Cheshire, England. His contribution to science was the discovery of neutrons.

Electron Cloud Model

Oct 31, 1935

Is an atom model where electrons are no longer depicted as particles moving around in a fixed orbit. That we aren't going to know where exactly where they are going to move around the nucleus, but an idea.

Bohr Planetary

Oct 31, 2013

The Bohr model is a modification of Rutherfords model. Planetary model in which the negetively charged electrons are orbiting a small positively charged nucleus just like planets do to the sun.