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This led to a series of atomic models with some quantum aspects, such as that of Arthur Erich Haas in 1910 [37]: 197 and the 1912 John William Nicholson atomic model with quantized angular momentum as h/2 π. [58] [59] The dynamical structure of these models was still classical, but in 1913, Bohr abandon the classical approach.
1914 James Franck and Gustav Hertz observe atomic excitation; 1915 Arnold Sommerfeld develops a modified Bohr atomic model with elliptic orbits to explain relativistic fine structure; 1916 Gilbert N. Lewis and Irving Langmuir formulate an electron shell model of chemical bonding; 1917 Albert Einstein introduces the idea of stimulated radiation ...
Memoir of John Dalton and History of the Atomic Theory. London: H. Bailliere. ISBN 978-1-4021-6437-8; Smyth, A. L. (1998). John Dalton, 1766–1844: A Bibliography of Works by and About Him, With an Annotated List of His Surviving Apparatus and Personal Effects. Manchester Literary and Philosophical Publications.
2650 BC: The oldest extant record of a unit of length, the cubit-rod ruler, is from Nippur. 2600 BC: The oldest attested evidence for the existence of units of weight, and weighing scales date to the Fourth Dynasty of Egypt, with Deben (unit) balance weights, excavated from the reign of Sneferu, though earlier usage has been proposed. [4]
Atomic theory (early) Democritus (c. 460 – c. 370 BC) [62] Founder of atomism in cosmology. Atomic theory (modern) Father Roger Boscovich (1711–1787) [63] First coherent description of atomic theory. John Dalton (1766–1844) [64] First scientific description of the atom as a building block for more complex structures. Atomic bomb
1803 – John Dalton: Atomic theory of matter [citation needed] 1806 – Thomas Young: Kinetic energy; 1814 – Augustin-Jean Fresnel: Wave theory of light, optical interference; 1820 – André-Marie Ampère, Jean-Baptiste Biot, and Félix Savart: Evidence for electromagnetic interactions (Biot–Savart law) 1822 – Joseph Fourier: Heat equation
An image from John Dalton's A New System of Chemical Philosophy, the first modern explanation of atomic theory.. This timeline of chemistry lists important works, discoveries, ideas, inventions, and experiments that significantly changed humanity's understanding of the modern science known as chemistry, defined as the scientific study of the composition of matter and of its interactions.
John William Nicholson is noted as the first to create an atomic model that quantized angular momentum as h/2π. [11] [12] Niels Bohr quoted him in his 1913 paper of the Bohr model of the atom. [13] 1912 – Victor Hess discovers the existence of cosmic radiation.