Timeline of Chemistry

By AndyR0ng

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Democritus

465 BC

First to propose that matter exists in the form of particles and called them atoms

Alchemists

1000 - 1650

Attempted to change metals into gold and make the elixir of life among many other things. The alchemists learned how to use metallic compounds and plant-derived materials to treat diseases

Sir Robert Doyle

1637 - 1691

Formulated the fundamental gas laws. First to propose the combination of small particles to form molecules. Differentiated between compounds and mixtures

Evangelista Torricelli

1643

Invented the mercury barometer

Joseph Priestly

1733 - 1804

Discovered oxygen, carbon monoxide, and nitrous oxide. Proposed electrical inverse-square law

C.W. Scheele

1742 - 1786

Discovered chlorine, tartaric acid, metal oxidation, and sensitivity of silver compounds to light

Nicholas Le Blanc

1742 - 1806

Invented process for making soda ash from sodium sulfate, limestone and coal

A.L. Lavoisier

1743 - 1794

Discovered nitrogen. Described the composition of many organic compounds. Sometimes regarded as the Father of Chemistry

C.L. Berthollet

1748 - 1822

Corrected Lavoiser’s theory of acids. Discovered bleaching ability of chlorine. Analyzed combining weights of atoms

Benjamin Franklin

1752

Demonstrated that lightning is electricity

John Dalton

1766 - 1844

Proposed atomic theory based upon measurable masses. Stated law of partial pressure of gases

Amedeo Avogadro

1776 - 1856

Proposed principle that equal volumes of gases contain the same number of molecules

Sir Humphry Davy

1778 - 1829

Laid foundation of electrochemistry. Studied electroysis of salts in water. Isolated sodium and potassium

J.L. Gay-Lussac

1778 - 1850

Discovered boron and iodine. Discovered acid-base indicators (litmus). Improved method for making sulfuric acid. Researched behavior of gases

J.J. Berzelius

1779 - 1850

Classified minerals according to their chemical composition. Discovered and isolated many elements (Se, Th, Si, Ti, Zr). Coined the terms 'isomer' and 'catalyst'

Dmitri Mendeléev

1834 - 1907

Discovered periodicity of the elements. Compiled the first Periodic Table with elements arranged into 7 groups

James Joules

1843

Experimentally demonstrated that heat is a form of energy

L. Boltzmann

1844 - 1906

Developed kinetic theory of gases. Viscosity and diffusion properties are summarized in Boltzmann’s Law

H. Becquerel

1851 - 1908

Discovered radioactivity of uranium and deflection of electrons by magnetic fields and gamma rays

Emil Fischer

1852 - 1919

Studied sugars, purines, ammonia, uric acid, enzymes, nitric acid. Pioneer research in sterochemistry

Sir J.J. Thomson

1856 - 1940

Research on cathode rays proved existence of electrons

A. Werner

1866 - 1919

Introduced concept of coordination theory of valence

Marie Curie

1867 - 1934

With Pierre Curie, discovered and isolated radium and polonium. Studied radioactivity of uranium

Sir Ernest Rutherford

1871 - 1937

Discovered that uranium radiation is composed of positively charged 'alpha' particles and negatively charged 'beta' particles. First to prove radioactive decay of heavy elements and to perform a transmutation reaction. Discovered half-life of radioactive elements. Established that the nucleus was small, dense, and positively charged. Assumed that electrons were outside the nucleus

James Clerk Maxwell

1873

Proposed that electric and magnetic fields filled space

G.J. Stoney

1874

Proposed that electricity consisted of discrete negative particles he named 'electrons'

Gilbert N. Lewis

1875 - 1946

Proposed electron-pair theory of acids and bases

F.W. Aston

1877 - 1945

Pioneer research on isotope separation by mass spectrograph

Sir William Crookes

1879

Discovered that cathode rays travel in straight lines, impart a negative charge, are deflected by electric and magnetic fields (indicating negative charge), cause glass to fluoresce, and cause pinwheels in their path to spin (indicating mass)

Henry G.J. Moseley

1887 - 1915

Discovered the relation between the frequency of the x-rays emitted by an element and its atomic number. His work led to the reorganization of the periodic table based on atomic number rather than atomic mass

Heinrich Hertz

1888

Discovered radio waves

Sir James Chadwick

1891 - 1974

Discovered the neutron

Harold C. Urey

1894 - 1981

One of the leaders of the Manhattan Project. Discovered deuterium

Joseph J. Thomson

1897

Discovered the electron. Used a cathode ray tube to experimentally determine the charge to mass ratio of an electron. Found that 'canal rays' were associated with the proton H+

Werner K. Heisenberg

1901 - 1976

Developed the orbital theory of chemical bonding. Described atoms using a formula related to the frequencies of spectral lines. Stated the Uncertainity Principle

Nagaoka

1903

Postulated a 'Saturnian' atom model with flat rings of electrons revolving about a positively charged particle

Abegg

1904

Discovered that inert gases have a stable electron configuration which results in their chemical inactivity

Ernest Rutherford and Thomas Royds

1909

Demonstrated that alpha particles are doubly ionized helium atoms

Robert Milliken

1913

Experimentally determined the charge and mass of an electron using an oil drop

Schodinger

1930

Described electrons as continuous clouds. Introduced 'wave mechanics' to mathematically describe the atom

Carl Anderson

1932

Discovered the positron

James Chadwick

1932

Discovered the neutron

Wolfgang Pauli

1933

Proposed the existence of neutrinos as a means of accounting for what appeared to be a violation of the law of conservation of energy in some nuclear reactions

Enrico Fermi

1934

Formulated his theory of beta decay

Glenn Seaborg

1941 - 1951

Synthesized several transuranium elements and suggested a revision to the layout of the periodic table