Atomic Theory Timeline


John Dalton


He created Dalton's Atomic Theory which said that all matter is composed of atoms, atoms cannot be made or destroyed,
all atoms of the same element are identical, different elements have different types of atoms, and a chemical reaction is a rearrangement of atoms. He also published Dalton's Law which stated total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture.

Eugen Goldstein


He concluded tha in addition to the cathode rays that travel from the negatively charged cathode toward the positively charged anode, there is another ray that travels in the opposite direction, from the anode toward the cathode. Goldstein called these canal rays because they pass through the channels in the cathode.

J.J. Thomson


Thomson proved that cathode rays were actually some speedily moving particles. After meausirng their speed and specific charge, he concluded that these "corpuscles" (electrons) were about 2000 times smaller in mass as compared to the hydrogen ion, the lightest-known atomic particle

Ernst Rutherford


He discovered aplha and beta radiation.

Max Planck

December 14, 1900

Planck combined the formulas of Wien and Rayleigh to form Planck;s radiation formula. He presented a theoretical explanation involving quanta of energy. He also discovered/created Planck's constant.

Ernst Rutherford


He co-discovered that radioactivity was a course of action in which atoms from one element disintegrated into atoms of a different element

Ernst Rutherford


He named gamma radiation and discovered it is more powerful than beta and alpha radiation.

Albert Einstein


Einstein created the theory of relaitivity, which laid the basis for the release of atomic theory. He also formulated the Special Theory of Relativity. He then established the law of mass through his famous formula E=mc2

Ernst Rutherford


He helped carry out the Geiger-Marsden experiment which allowed him to understanf the nuclear nature of atoms

Robert Millikan


Millikan’s earliest major success was the accurae determinaton of the charge carried by an electron using the “falling-drop method”. He also proved that this quantity was a constant for all electrons, which demonstrated the atomic structure of electricity.

Ernst Rutherford


The Rutherford model of the atom explained that a small positive charged nucleus was orbited by electrons

Robert Millikan

1912 - 1915

Millikan verified Einsteins’s very important photoelectric equation experimentally, and made the first direct photoelectric determination of Planck’s constant.

Henry Moseley


He discovered systematic relation between wavelength and atomic number which is called Moseley's Law. He also predicted a number of missing elements and their atomic numbers.

Neils Bohr


Bohr completed his theory of atomic structure in 1913. He stated that electrons have set energy levels and created a realistic model. His atomic theory was a combination of Rutherford’s work and ideas of the atom, with Planck’s Quantum Theory. Bohr received the Nobel Prize in Physics for his research in the atomic structure in1922.

Ernst Rutherford


He was the first person to transfer one element into another through a nuclear reaction.

Ernst Rutherford


He gave his theory about the existence of neutrons.

Werner Heisenberg


He formulated the quantum theory of ferromagnetism, the neutron-proton model of the nucleus, and the S-matrix theory in particle scattering. He also suggested the unified field theory a.k.a the "world formula". He is known for one of the earliest breakthroughs to quantum mechanics.

Erwin Schrodinger


He is known for the tremendous discovery of the Schrodinger Wave Equation. The Schrodinger Equation is a wave equation in terms of the wavefunction that predicts logically and precisely the probability of events or outcome.

Louis deBroglie


He thought about dual nature of light; the wave - particle duality. He suggested that matter might behaveina similar matter. He made the theory of electron waves, and resolved and offered an explanation to a question that was brought up by calculations of the motion of electrons within atoms.

James Chadwick


Chadwick discovered the exsistence of the neutron and that it had 0.1 percent more mass than a proton. This was one of the most important scientific discoveries of the twentieth century. He received the Noble Prize for discovery in 1935.

Other Scientists

Joseph Priestly


discovered oxygen, carbon monoxide, and nitrogen dioxide

Antoine Lavoisier


Father of modern chemistry

Antoine Lavoisier


Law of conservation of mass

Alssandro Volta



Alessandro Volta


Electrochemical cell

Michael Faraday


first electric discovery

Michael Faraday

1832 - 1833

discovered laws of electrochemistry

Alfred Nobel


Dynamite, Nobel Prize

Louis Pasteur


Pasteurization process

Henri Becquerel

May 18, 1896


Marie Curie



Sir Frederick Banting

1921 - 1922

Isolated insulin

Philo Farnsworth

September 7, 1927


Wallace Carothers

April 1930


Gugliemo Marconi



Leo Szilard


Nuclear chain reactions

Wallace Carothers

October 27, 1938


Leo Szilard


Atomic bomb

Kary Mullis

1984 - 1985

Polymerase chain reaction

Historical Events

Gutenburg printing press


Discovery of the Americas

October 12, 1492

Reformation of the Catholic Church


Galileo convicted of Heresy


Declaration of Independence

July 4, 1776

Civil War

1861 - 1865

First transcontinental railroad in U.S.


Assassination of Archduke Ferdinand

June 28, 1914

Bolshevik Revolution


Treaty of Versailles

June 28, 1919

Bombing of Pearl Harbor

December 7, 1941

First Cellular Phone


Initial concept for World Wide Web (Internet)

1990 - 2000