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  2. Eddington number - Wikipedia

    en.wikipedia.org/wiki/Eddington_number

    He related α to the Eddington number, which was his estimate of the number of protons in the universe. [2] This led him in 1929 to conjecture that α was exactly 1/136. [3] He devised a "proof" that N Edd = 136 × 2 256, or about 1.57 × 10 79. Other physicists did not adopt this conjecture and did not accept his argument.

  3. Chemical element - Wikipedia

    en.wikipedia.org/wiki/Chemical_element

    The mass number of an element, A, is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes of a given element are distinguished by their mass number, which is written as a superscript on the left hand side of the chemical symbol (e.g., 238 U). The mass number is always an integer and has units of "nucleons".

  4. Atomic number - Wikipedia

    en.wikipedia.org/wiki/Atomic_number

    The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of its atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (n p) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ...

  5. Proton - Wikipedia

    en.wikipedia.org/wiki/Proton

    The number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number (represented by the symbol Z). Since each element is identified by the number of protons in its nucleus, each element has its own atomic number, which determines the number of atomic electrons and consequently the chemical ...

  6. Scientific notation - Wikipedia

    en.wikipedia.org/wiki/Scientific_notation

    Converting a number from scientific notation to decimal notation, first remove the × 10 n on the end, then shift the decimal separator n digits to the right (positive n) or left (negative n). The number 1.2304 × 10 6 would have its decimal separator shifted 6 digits to the right and become 1,230,400 , while −4.0321 × 10 −3 would have its ...

  7. Greek letters used in mathematics, science, and engineering

    en.wikipedia.org/wiki/Greek_letters_used_in...

    an asymptotic lower bound notation related to big O notation; in probability theory and statistical mechanics, the support; a solid angle [79] [80] the omega baryon; the arithmetic function counting a number's prime factors counted with multiplicity; the density parameter in cosmology [81] the first uncountable ordinal (also written as ω 1) [82]

  8. Table of nuclides - Wikipedia

    en.wikipedia.org/wiki/Table_of_nuclides

    A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.

  9. Hydron (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Hydron_(chemistry)

    In chemistry, the hydron, informally called proton, [2] is the cationic form of atomic hydrogen, represented with the symbol H +The general term "hydron", endorsed by IUPAC, encompasses cations of hydrogen regardless of isotope: thus it refers collectively to protons (1 H +) for the protium isotope, deuterons (2 H + or D +) for the deuterium isotope, and tritons (3 H + or T +) for the tritium ...