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  2. History of chemistry - Wikipedia

    en.wikipedia.org/wiki/History_of_chemistry

    Lewis's theory of chemical bonding continued to evolve and, in 1916, he published his seminal article "The Atom of the Molecule", which suggested that a chemical bond is a pair of electrons shared by two atoms. Lewis's model equated the classical chemical bond with the sharing of a pair of electrons between the two bonded atoms. Lewis ...

  3. History of molecular theory - Wikipedia

    en.wikipedia.org/wiki/History_of_molecular_theory

    This, according to Lewis, meant that bonding occurred when two electrons formed a shared edge between two complete cubes. On these views, in his famous 1916 article The Atom and the Molecule , Lewis introduced the "Lewis structure" to represent atoms and molecules, where dots represent electrons and lines represent covalent bonds .

  4. History of the periodic table - Wikipedia

    en.wikipedia.org/wiki/History_of_the_periodic_table

    This is an accepted version of this page This is the latest accepted revision, reviewed on 8 March 2025. Development of the table of chemical elements The American chemist Glenn T. Seaborg —after whom the element seaborgium is named—standing in front of a periodic table, May 19, 1950 Part of a series on the Periodic table Periodic table forms 18-column 32-column Alternative and extended ...

  5. Chemical revolution - Wikipedia

    en.wikipedia.org/wiki/Chemical_revolution

    John Dalton was an English chemist who developed the idea of atomic theory of chemical elements. Dalton's atomic theory of chemical elements assumed that each element had unique atoms associated with and specific to that atom. [19]

  6. Electron - Wikipedia

    en.wikipedia.org/wiki/Electron

    The wave function of fermions, including electrons, is antisymmetric, meaning that it changes sign when two electrons are swapped; that is, ψ(r 1, r 2) = −ψ(r 2, r 1), where the variables r 1 and r 2 correspond to the first and second electrons, respectively. Since the absolute value is not changed by a sign swap, this corresponds to equal ...

  7. Mendeleev's predicted elements - Wikipedia

    en.wikipedia.org/wiki/Mendeleev's_predicted_elements

    The lightest of the Group 0 gases, the first in the periodic table, was assigned a theoretical atomic mass between 5.3 × 10 −11 u and 9.6 × 10 −7 u. The kinetic velocity of this gas was calculated by Mendeleev to be 2,500,000 meters per second.

  8. Prout's hypothesis - Wikipedia

    en.wikipedia.org/wiki/Prout's_hypothesis

    According to the whole number rule proposed by Francis Aston, the mass of an isotope is roughly, but not exactly, its mass number A (Z + N) times an atomic mass unit (u), plus or minus binding energy discrepancy – atomic mass unit being the modern approximation for "mass of a proton, neutron, or hydrogen atom".

  9. Periodic trends - Wikipedia

    en.wikipedia.org/wiki/Periodic_trends

    The atomic radius is half of the distance between two nuclei of two atoms. The atomic radius is the distance from the atomic nucleus to the outermost electron orbital in an atom . In general, the atomic radius decreases as we move from left-to-right in a period , and it increases when we go down a group .