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  2. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    Modern atomic theory is not based on these old concepts. [2] [3] In the early 19th century, the scientist John Dalton noticed that chemical substances seemed to combine with each other by discrete and consistent units of weight, and he decided to use the word atom to refer to these units. [4]

  3. Atomism - Wikipedia

    en.wikipedia.org/wiki/Atomism

    He described atomic theory as a 'Thoroughly materialistic bit of joiners work'. [77] English chemist Alexander Williamson used his Presidential Address to the London Chemical Society in 1869 [78] to defend the atomic theory against its critics and doubters. This in turn led to further meetings at which the positivists again attacked the ...

  4. Timeline of atomic and subatomic physics - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_atomic_and...

    1936 Eugene Wigner develops the theory of neutron absorption by atomic nuclei; 1936 Hermann Arthur Jahn and Edward Teller present their systematic study of the symmetry types for which the Jahn–Teller effect is expected [8] 1937 Carl Anderson proves experimentally the existence of the pion predicted by Yukawa's theory.

  5. History of chemistry - Wikipedia

    en.wikipedia.org/wiki/History_of_chemistry

    The early theory of atomism can be traced back to ancient Greece. Greek atomism was made popular by the Greek philosopher Democritus, who declared that matter is composed of indivisible and indestructible particles called "atomos" around 380 BC. Earlier, Leucippus also declared that atoms were the most indivisible part of matter.

  6. Discovery of the neutron - Wikipedia

    en.wikipedia.org/wiki/Discovery_of_the_neutron

    [70] [76] Fermi's theory requires the neutron to be a spin-1 ⁄ 2 particle. The theory preserved the principle of conservation of energy, which had been thrown into question by the continuous energy distribution of beta particles. The basic theory for beta decay proposed by Fermi was the first to show how particles could be created and destroyed.

  7. Timeline of chemistry - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_chemistry

    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.

  8. Atomism (social) - Wikipedia

    en.wikipedia.org/wiki/Atomism_(social)

    Atomism or social atomism is a sociological theory arising from the scientific notion atomic theory, coined by the ancient Greek philosopher Democritus and the Roman philosopher Lucretius. In the scientific rendering of the word, atomism refers to the notion that all matter in the universe is composed of basic indivisible components, or atoms.

  9. Timeline of quantum mechanics - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_quantum_mechanics

    1963 – Eugene P. Wigner lays the foundation for the theory of symmetries in quantum mechanics as well as for basic research into the structure of the atomic nucleus; makes important "contributions to the theory of the atomic nucleus and the elementary particles, particularly through the discovery and application of fundamental symmetry ...