Atomic Theory

Events

Democritus

400 BCE

:Born in Athens, lived from 460 to 370 bce, and studied philosophy, and geometry. Came up with the atomic theory, which states that the smallest particle was the atom, and the universe was made of atoms.

Aristotle

Approx. 325 bce

Born 384 b.c.e. Died 322 b.c.e Studied a wide variety of things under plato at the Academy , in Athens. Even taught Alexander the Great. Did not believe in the atomic theory. He believed everything was made of fire, water air, and earth just in large or small amounts, and mixtures of those 4. H taught this belief to his students, and most the world agreed with him.

Evangelista Torricelli

1643

Torricelli’s law is the basic principle behind the barometer. Torricelli’s discovery proved that air has weight and can push down a column of mercury.

Joseph Priestly

1772

Joseph Priestly discovered oxygen which helped to form the basis of modern chemistry

Antoine Lavoisier

1789

1743-1794 devised the conservation of mass law.

John Dalton

1803

John Dalton*: 1766-1844 Lived and worked in England. Studied meteorology. His atomic theory states, elements are made of tiny particles, and atoms of the same element are identical. Same mass, same density. All atoms of different substances have different weight. Compounds have a fixed ratio of atoms

Michael Faraday

1821

His main discoveries include the principles underlying electromagnetic induction, diamagnetism and electrolysis.

Henri Becquerel

1896

Henri Becquerel was using naturally fluorescent minerals to study the properties of x-rays, discovering radioactivity

JJ Thompson

1897

1856-1940 Studied mathematics and physics. Stated that atoms are made of positive, and negative cores. Created the plum pudding model.

Marie Curie

1898

1867-1934 Studied radioactivity, and discovered radioactive properties in plutonium, and radium. She was the first to win 2 nobel prizes.

Max Planck

1900

Originated the quantum theory which says that one photon of light carries 1 quantum of energy

Albert Einstein

1905

Albert Einstein became famous for the theory of relativity, which laid the basis for the release of atomic energy

Robert Millikan

1909

Conducted the oil drop experiment which determined the size of charge on an electron

Ernest Rutherford

1911

1871-1937. Theorized that the nucleus was dense, and small while the electrons were outside the nucleus. He did this by shining several lasers through gold foil.

Niels Bohr

1913

Devised and explanation of atomic structure that shows a pattern of the periodic table. Model shows multiple orbits/shells of electrons

Louis De Brogile

1923

1892-1987 Found out electrons have 2 nature's similar to wave and particles. Particle wave/ duality supported by Einstein.

Erwin Schrödinger

1926

A powerful model of the atom was developed by Erwin Schrödinger in 1926. Schrödinger combined the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom.

James Chadwick

1932

Chadwick discovered the neutron of an atom