Sodium average atomic mass

We can solve this problem by using the average atomic mass for sodium (see Table 8.1) of 22.99 amu. The appropriate equivalence statement is... 

EXERCISE 8.5 Calculate the molar mass for sodium sulfate, Na2S04. A sample of sodium sulfate with a mass of 300.0 g represents what number of moles of sodium For average atomic masses, look sulfate ... 

When the idea of relative atomic mass was first put forward, some chemists started to wonder whether there was a connection between the RAM of an element and its properties. One of these chemists, Dobereiner, in 1829, noticed that there were groups of three elements (triads) which had very similar chemical properties and in which the RAM of the middle element was almost exactly the average of the other two elements in the triad (these groups became knovm as Dobereiner s Triads). One triad was the three elements lithium, sodium and potassium all are soft metals, are highly reactive and have to be stored under oil. Their RAMs are lithium 7, sodium 23, potassium 39. As you can see, sodium s RAM is the average of 7 and 39. 

What is the weighted average mass in atomic mass units (u) of each atom of the elements (a) sodium and (b) oxygen ... 

The average mass of one atom of sodium, in units of amu, is numerically identical to the mass of Avogadro s number of atoms, expressed in units of grams. Hence the molar mass of sodium is 22.99 g Na/mol. 

Ddbereiner triads A set of triads of chemically similar elements noted by Jo-hatm Dobereiner (1780-1849) in 1817. Even with the inaccurate atomic mass data of the day it was observed that when each triad was arranged in order of increasing atomic mass, then ffie mass of the central member was approximately the average of the values for the other two. The chemical and physical properties were similarly related. The triads are now recognized as consecutive members of the groups of the periodic table. Examples are lithium, sodium, and potassium calcium, strontium, and barium and chlorine, bromine, and iodine. iiqilElHWJlIHIH. ... 

The product received the name HA-1 . Its protein content is not more than 0.2% (by J. Lowry [26], calculated for albumin), its static viscosity is in the range 14.5-21 dl/g (determined by a Ubbelohde type viscometer at 25°C at 0.15M), its solution of sodium chloride is at pH 7.0, and the UV absorption of 1.0% solution at 257 and 280nm is not more than l.OAU). As determined on the instrument with inductive coupled plasma (ICP), the content of the sulfated mucopolysaccharides did not exceed 0.07% based on the sulfur content. The iron content did not exceed 10 ppm by the spectral atomic absorption or by ICP. The stability of the buffer isotonic solutions at pH 7.0 of HA-1, which underwent the normal ageing and thermal sterilization, was measured by the static viscosity and described as the reduction of the average molecular mass. The stability of HA-1 did not exceed the following limit data ... 

The average mass of one sodium atom is 22.99 amu. This may be formatted as the conversion factor ... 

If an average sodium atom has a mass of 3.82 X 10 g, what is the mass of a magnesium atom in grams ... 

The simple electronic structure of sodium also renders the application of other types of models relatively easy and extendable to relatively large sizes. See e.g. Hiickel calculations and MC structural search (R. Poteau and F. Spiegelmann, Phys. Rev. B 45, 1878 (1992) and J. Chem. Phys. 98, 6540 (1993) Erratum 99, 10089 (1993)) or the so-called spherically averaged pseudopotential (SAPS) model (M. D. Glossman, J. A. Alonso and M. P. Iniguez, Phys. Rev. B 47, 4747 (1993)). This is a simplified atomistic scheme, in which the external potential (written as the sum of the atomic pseudopotentials) acting on the electrons is developed in spherical harmonics around the cluster center of mass, and only the spherical component is retained in the solution of the KS equations. 

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