Timeline of Chemistry

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

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

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

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

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

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

Experimentally demonstrated that heat is a form of energy

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

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

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

Research on cathode rays proved existence of electrons

Introduced concept of coordination theory of valence

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

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

Proposed that electric and magnetic fields filled space

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

Proposed electron-pair theory of acids and bases

Pioneer research on isotope separation by mass spectrograph

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)

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

Discovered radio waves

Discovered the neutron

One of the leaders of the Manhattan Project. Discovered deuterium

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+

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

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

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

Demonstrated that alpha particles are doubly ionized helium atoms

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

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

Discovered the positron

Discovered the neutron

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

Formulated his theory of beta decay

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