Avogadro's number


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Related to Avogadro's number: Avogadro's constant

Avogadro's number

(ävōgä`drō) [for Amedeo AvogadroAvogadro, Amedeo, conte di Quaregna
, 1776–1856, Italian physicist, b. Turin. He became professor of physics at the Univ. of Turin in 1820. In 1811 he advanced the hypothesis, since known as Avogadro's law, that equal volumes of gases under identical conditions of pressure
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], number of particles contained in one molemole,
in chemistry, a quantity of particles of any type equal to Avogadro's number, or 6.02×1023 particles. One gram-molecular weight of any molecular substance contains exactly one mole of molecules.
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 of any substance; it is equal to 602,252,000,000,000,000,000,000, or in scientific notation, 6.02252×1023. For example, 12.011 grams of carbon (one mole of carbon) contains 6.02252×1023 carbon atoms, and 180.16 grams of glucose, C6H12O6, contains 6.02252×1023 molecules of glucose. Avogadro's number is determined by calculating the spacing of the atoms in a crystalline solid through X-ray methods and combining this data with the measured volume of one mole of the solid to obtain the number of molecules per molar volume.

Avogadro's number

[¦a·və¦gäd·drōz ‚nəm·bər]
(physics)
The number (6.02 × 1023) of molecules in a gram-molecular weight of a substance.
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where Pc = particle concentration in nmol/L, F = proportion of particles with a single charge (from Fuch distribution (19)), Pn = particle number counted in size range, [10.sup.18] = mol to nmol and nL to L; D = dilution of sample, Fr = flow rate in nL/min, 600 = 0.1-s bins per min, A = Avogadro's number, M = number of 0.1-s bins included in size range, and R = lipoprotein recovery after ultracentrifugation (50%).
Coupled with that discovery was the well known quantitative determination of the charge-to-mass ratio, "e/m", (the basis of mass-spectrometry developed later) of the electron, and its absolute charge "e", by Townsend and, more reliably, by Millikan [7], and ultimately, with high accuracy, from the ratio, F/[N.sub.A], of Faraday's constant to Avogadro's number. Had Faraday himself, around 1834, made the conclusion reached by von Helmholtz in 1881 about the "atomic" nature of electricity, one could speculate that the development of atomic, ionic and molecular aspects of chemistry and physics might have been ad vanced by some forty years.
Currently, Avogadro's number is rooted in the exact number of atoms present in 12 grams of the isotope carbon-12.
Note even Avogadro's Number. I presume he said less than [10.sup.9] (actually [10.sup.8]), and a typo translated it as 109.
Where N is Avogadro's number, I3CH2 is the surface energy of a hypothetical substance that contain only methylene groups and [alpha]CH2 is the cross-sectional area of a methylene group ([alpha]CH2=0.06 nm2).
In the past decade, researchers have found that homeopathic dilutions, beyond Avogadro's number, of gold (Aurum metallicum), copper (Cuprum metallicum), and the plant Gelsemium contain nanoparticles of the original materials.
where [N.sub.A] is Avogadro's number, [rho] is the density, M is the molecular weight, [R.sub.LL] is the molar refraction ([cm.sup.3] [mol.sup.-1]), and V is the polymer molar volume ([cm.sup.3] [mol.sup.-1]).
While detection limits of ppt and ppq for organochlorines such as PCBs and dioxins seem low, remember that Avogadro's Number is very large.
In classical physics applications, in statistical mechanics--that is, the theory of gases--it can go to three times Avogadro's number, the number of atoms in a gram-mole of an element or compound, Alder says.
These solutions are described as dilutions beyond Avogadro's number, because the antigen is no longer detectable by scanning electron microscopy.
where M is the molar mass of the ferrite, a is the lattice parameter, and NA is Avogadro's number.