Atomic weight, weighted average

Atomic weight Weighted average of the masses of the constituent isotopes of an element the relative mass of atoms of different elements. 

American Society of Mechanical Engineers American Society for Testing and Materials atomic number atomic weight average... 

Table 2.2 gives the masses to four or five decimal places for the common nuclides it also gives the familiar atomic weights (average weights for the elements). 

SECTION Z4 The atomic mass scale is defined by assigning a mass of exactly 12 amu to a atom. The atomic weight (average atomic mass) of an element can be calculated from the relative abundances and masses of that elements isotopes. The mass spectrometer provides the most direct and accurate means of experimentally measuring atomic (and molecular) weights. 

Only two isotopes of copper occur naturally, Cu (atomic mass = 62.9296 amu abundance 69.17%) and (atomic mass = 64.9278 amu abundance 30.83%). Calculate the atomic weight (average atomic mass) of copper. 

Temary and quaternary semiconductors are theoretically described by the virtual crystal approximation (VGA) [7], Within the VGA, ternary alloys with the composition AB are considered to contain two sublattices. One of them is occupied only by atoms A, the other is occupied by atoms B or G. The second sublattice consists of virtual atoms, represented by a weighted average of atoms B and G. Many physical properties of ternary alloys are then expressed as weighted linear combinations of the corresponding properties of the two binary compounds. For example, the lattice constant d dependence on composition is written as ... 

Lead, atomic number 82, is a member of Group 14 (IVA) of the Periodic Table. Ordinary lead is bluish grey and is a mixture of isotopes of mass number 204 (15%), 206 (23.6%), 207 (22.6%), and 208 (52.3%). The average atomic weight of lead from different origins may vary as much as 0.04 units. The stable isotopes are products of decay of three naturally radioactive elements (see Radioactivity, natural) comes from the uranium series (see Uraniumand... 

The moduli of metals, ceramics and glassy polymers below Tq reflect the stiffness of the bonds which link the atoms. Glasses and glassy polymers above are leathers, rubbers or viscous liquids, and have much lower moduli. Composites have moduli which are a weighted average of those of their components. 

For the most part, the elemental analysis data for the blends are consistent with a weighted average of the individual components. Also shown is the elemental analysis for some of the soluble products form WVGS 13423 in Table 10 As was observed for the WVGS 13421 products, hydrogenation increased the total hydrogen content and decreased the atomic C/H ratio. 

These equilibria effect a rapid exchange of N atoms between the various species and only a single N nmr signal is seen at the weighted average position of HNO3, [NOa]" " and [N03]. They also account for the high electrical conductivity of the pure (stoichiometric) liquid (Table 11.13), and are an important factor in the chemical reactions of nitric acid and its non-aqueous solutions see below. 

Atomic mass (Section 1.1) The weighted average mass of an element s naturally occurring isotopes. 

Relative masses of atoms of different elements are expressed in terms of their atomic masses (often referred to as atomic weights). The atomic mass of an element indicates how heavy, on the average, one atom of that element is compared with an atom of another element... 

How much would 0.754 mole of chlorine-35 atoms weigh How much would 0.246 mole of chlorine-37 atoms weigh What is the weight of a mole of average atoms in a mixture of the above samples What is the atomic weight of the naturally occurring mixture of these two isotopes of chlorine ... 

The problem with triads, as well as the other important numerical hypothesis due to Prout, is easy to discern in retrospect. It is simply that atomic weight, which both concepts draw upon, is not the most fundamental quantity that can be used to systematize the elements. The atomic weight of any element depends on the particular geological origin of the sample examined. In addition, the atomic weight of any particular element is an average of several isotopes of the particular element. 

Moreover, if we consider atomic numbers instead of atomic weights for the triads discovered in Ihe 19th century, it turns out that the atomic number of Ihe middle element is exactly the average vt the other two elements Indeed, about halt of al Ihe possible triads in the modern periodic table are exact in this sense However many other potential triads are not even approximately correct in that the atomic number of the middle dement is nowhere near Ihe average of Ihe other two... 

The tabulated molar mass of an element divided by Avogadro s number is the average mass per atom of that element, but it is not the exact mass of an individual nucleus. There are two reasons for this. First, molar masses refer to neutral atoms. The tabulated molar mass of an element includes the mass of its electrons in addition to the mass of its nucleus. Consequently, the mass of Z electrons must be subtracted from the isotopic molar mass in computing the energy of formation of a nuclide. Second, molar masses of the elements are weighted averages of... 

The atomic mass of an element is the weighted average mass of the isotopes of that element. Based on this definition, which of these does NOT show the correct atomic mass for an element ... 

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