The whole number rule states that the masses of the isotopes are whole number multiples of the mass of the hydrogen atom. The rule is a modified version of Prout's hypothesis proposed in 1815, to the effect that atomic weights are multiples of the weight of the hydrogen atom.
In 1920, Francis W. Aston demonstrated through the use of a mass spectrometer that apparent deviations from Prout's hypothesis are predominantly due to the existence of isotopes; they are secondarily due to binding energy, as mass defect. The modern form of the whole number rule is that the atomic mass of a given elemental isotope is approximately the mass number (number of protons plus neutrons) times an atomic mass unit (approximate mass of a proton, neutron, or hydrogen-1 atom). This rule predicts the atomic mass of nuclides and isotopes with an error of at most 1%.
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496 is most notable for being a perfect number, and one of the earliest numbers to be recognized as such ... As a perfect number, it is tied to the Mersenne prime 31, 25 - 1, with 24 ( 25 - 1 ) yielding 496 ... Also related to its being a perfect number, 496 is a harmonic divisor number, since the number of proper divisors of 496 divided by the sum of the reciprocals of its divisors, 1, 2, 4, 8, 16, 31, 62 ...
... This article discusses the number thirty-eight. 39 ... → 38 ← 39 ... → List of numbers — Integers 90 ... → Cardinal thirty-eight Ordinal 38th (thirty-eighth ...
39 is the smallest natural number which has three partitions into three parts which all give the same product when multiplied {25, 8, 6}, {24, 10, 5}, {20, 15, 4} ... The thirteenth Perrin number is 39, which comes after 17, 22, 29 (it is the sum of the first two mentioned) ... which is obviously more than 39 twice, 39 is a Størmer number ...
... William Prout Atomic mass Binding energy Law of definite proportions Mass number Nuclear Models ...
... their first, "'39" does in fact fall in the thirty-ninth position The retired jersey number of former baseball player Roy Campanella The book series "The 39 Clues" revolves around 39 clues hidden around ... History The number of signers to the United States Constitution, out of 55 members of the Philadelphia Convention delegates The traditional number of times citizens of Ancient Rome hit their slaves ... chat slang for "thank you" when written with numbers (3=san 9=kyu) Pier 39 in San Francisco The number of the French department Jura In Afghanistan, the number 39 is considered ...
Famous quotes containing the words rule and/or number:
“Now, since our condition accommodates things to itself, and transforms them according to itself, we no longer know things in their reality; for nothing comes to us that is not altered and falsified by our Senses. When the compass, the square, and the rule are untrue, all the calculations drawn from them, all the buildings erected by their measure, are of necessity also defective and out of plumb. The uncertainty of our senses renders uncertain everything that they produce.”
—Michel de Montaigne (1533–1592)
“Hence, a generative grammar must be a system of rules that can iterate to generate an indefinitely large number of structures. This system of rules can be analyzed into the three major components of a generative grammar: the syntactic, phonological, and semantic components.”
—Noam Chomsky (b. 1928)