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  2. Atomic nucleus - Wikipedia

    en.wikipedia.org/wiki/Atomic_nucleus

    The adoption of the term "nucleus" to atomic theory, however, was not immediate. In 1916, for example, Gilbert N. Lewis stated, in his famous article The Atom and the Molecule, that "the atom is composed of the kernel and an outer atom or shell." [12] Similarly, the term kern meaning kernel is used for nucleus in German and Dutch.

  3. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    [35]: 118 Moreover, the periodic table could predict how many atoms of other elements that an atom could bond with — e.g., germanium and carbon are in the same group on the table and their atoms both combine with two oxygen atoms each (GeO 2 and CO 2). Mendeleev found these patterns validated atomic theory because it showed that the elements ...

  4. Rutherford model - Wikipedia

    en.wikipedia.org/wiki/Rutherford_model

    This was in a gold atom known to be 10 −10 metres or so in radius—a very surprising finding, as it implied a strong central charge less than 1/3000th of the diameter of the atom. The Rutherford model served to concentrate a great deal of the atom's charge and mass to a very small core, but did not attribute any structure to the remaining ...

  5. Discovery of nuclear fission - Wikipedia

    en.wikipedia.org/wiki/Discovery_of_nuclear_fission

    Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei and often other particles. The fission process often produces gamma rays and releases a very large amount of energy, even by the energetic standards of radioactive decay.

  6. Bohr model - Wikipedia

    en.wikipedia.org/wiki/Bohr_model

    The Bohr model of the hydrogen atom (Z = 1) or a hydrogen-like ion (Z > 1), where the negatively charged electron confined to an atomic shell encircles a small, positively charged atomic nucleus and where an electron jumps between orbits, is accompanied by an emitted or absorbed amount of electromagnetic energy (hν). [1]

  7. Two-electron atom - Wikipedia

    en.wikipedia.org/wiki/Two-electron_atom

    The optical spectrum of the two electron atom has two systems of lines. A para system of single lines, and an ortho system of triplets (closely spaced group of three lines). The energy levels in the atom for the single lines are indicated by 1 S 0 1 P 1 1 D 2 1 F 3 etc., and for the triplets, some energy levels are split: 3 S 1 3 P 2 3 P 1 3 P ...

  8. Atom (measure theory) - Wikipedia

    en.wikipedia.org/wiki/Atom_(measure_theory)

    Consider the set X = {1, 2, ..., 9, 10} and let the sigma-algebra be the power set of X. Define the measure of a set to be its cardinality, that is, the number of elements in the set. Then, each of the singletons {i}, for i = 1, 2, ..., 9, 10 is an atom. Consider the Lebesgue measure on the real line. This measure has no atoms.

  9. Atom (order theory) - Wikipedia

    en.wikipedia.org/wiki/Atom_(order_theory)

    In the mathematical field of order theory, an element a of a partially ordered set with least element 0 is an atom if 0 < a and there is no x such that 0 < x < a. Equivalently, one may define an atom to be an element that is minimal among the non-zero elements, or alternatively an element that covers the least element 0 .