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formulas_chapter12_section6

# formulas_chapter12_section6 - NA = Avogadro's number m =...

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N A = Avogadro’s number m = mass of the sample m * = mass of one atom N = number of atoms in the sample m = N m * If N = N A , then m = M, the molar mass; and M = N A m * . n = number of moles of atoms in the sample n = m / M and n = N / N A . (Note that combining these gives m / N = M / N A .) V = volume of the sample d = m / V = M / V m , where V m is molar volume, V m = V / n. V * = volume of one atom = (4/3) π r 3 , where r is the atomic radius. The volume of the N atoms in the sample is obtained by multiplying V * by N. Observe that N V * is not the volume of the sample, since the sample contains some empty space in addition to the atoms. The fraction of the sample that is occupied by atoms is f = N V * / V and is called the packing fraction. N cell = number of unit cells in the sample x cell = number of atoms in a unit cell m cell = mass in a unit cell V cell = volume of a cubic unit cell = a 3 , where a is the length of a side of a cubic unit cell (also called the edge length). For a simple cubic unit cell, a = 2r ; for a body-centered cubic or bcc unit cell,

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formulas_chapter12_section6 - NA = Avogadro's number m =...

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