Timeline: atom timeline

401 BCE

Aristotle

said atoms didn't exist

400 BCE

Democritus

adopted the atomic theory: Said all matter was formed of different types of tiny discrete particles and that the properties of these particles also determine the properties of the matter

Oct 4, 1786

Antonie Lavosier

created the law of conservation of matter

Oct 4, 1793

Joseph Proust

created the proust law

Oct 4, 1800

John Dalton

said all matter was made of atoms, all atoms are indivisible and indestructible. All atoms of a given element are identical in mass and properties. also that compounds were made of 2 different atoms and that a chemical reaction is the atoms rearranged

Oct 4, 1811

Amadeo Avagadro

first scientist to realize that elements could exist as molecules rather than as individual atoms

Oct 4, 1873

William Crookes

discovered the atomic weight

Oct 4, 1896

Henri Becquerel

discovered radioactivity

Oct 4, 1900

Ernest Rutherford

made the nuclear structure of an atom

Oct 4, 1900

Max Planck

found a way to describe the behavior of particles of the atomic scale

Oct 4, 1903

Madame Curie

pioneer radioactivity

Oct 4, 1904

J.J. Thomson

suggested the model of the atom in a sphere of positive matter which electrons are positioned by electrostatic forces

Oct 4, 1908

Robert Millikan

measured the charge of an electron

Oct 4, 1913

Henry Moseley

published the results of his measurements of the wavelengths of the X-ray spectral lines of a number of elements which showed that the ordering of the wavelengths of the X-ray emissions of the elements coincided with the ordering of the elements by atomic number.