Mass of nuclides

Because the masses of nuclides are so small, they are normally reported as a multiple of the atomic mass constant, ma (formerly atomic mass unit, amu). The atomic mass constant is defined as exactly V12 the mass of one atom of carbon-12 ... 

Although binding energy is a term referring to the nucleus, it is more convenient to use the mass of the whole atom (nuclide) in calculations, since these are the masses that are given in tables. If M(X) is the atomic mass of nuclide X,... 

Arrhenius activation energy 55 astronomical unit 110 asymmetry parameter 23 atmosphere 112 atomic mass 20, 41, 94 atomic mass constant 20, 41, 89 atomic mass unit 20, 41, 75, 89, 111 atomic masses of nuclides 98-104 atomic number 20, 44 atomic orbital basis function 17, 19 atomic scattering factor 36 atomic states 28 atomic units 76, 120 atomic weight 41, 94 atomization 51, 53 attenuance 32 atto 74... 

It is now recommended by the International Union of Pure and Applied Chemistry that the nuclide should be used as the basis of a unified scale. To bring them to the carbon-12 scale, atomic masses on the chemical scale must be reduced by 43 parts per million (multiplied by 0.999957). No atomic mass is changed by more than 4 in the last place quoted in the 1957 table, and few of these have been established with certainty to better than 5 in the last place. The carbon-12 scale is very suitable for expressing the masses of nuclides and has the advantage that very few of the present figures are affected by as much as their limits of error. 

Precise determinations of the masses of nuclides have shown that they are not simply the sums of the individual masses of their component protons and neutrons. When these units or nucleons combine to form a nucleus there is a change of potential and kinetic energy which appears as a change in mass. Einstein showed the energy created by the destruction of mass and the mass destroyed to be related thus ... 

Atomic weight (A - The ratio of the average mass per atom of an element to 1/12 of the mass of nuclide C. An atomic weight can be defined for a sample of any given isotopic composition. The standard atomic weight refers to a sample of normal terrestrial isotopic composition. The term relative atomic mass is synonymous with atomic weight. [2]... 

We would wish to follow a small packet of contaminated water and study the fate of the mass of nuclides it carries. In the most idealised case the packet keeps its identity from start to finish. There are a number of mechanisms that disturbs this ideal picture. Mixing with other water packages and sorption on the solid material the packet passes are of main concern here. 

Aston discovered in 1923 that every isotopic mass is characterized by a small mass defect that is, the masses of nuclides are not simple multiples of a fundamental unit. Since Aston s discovery, considerable woik has been performed to measure accurately the masses of all the known stable nuclides (mainly by the use of mass spectrometers). Table 1.1 (in Chapter 1) contains the results of this work for the elements commonly found in organic compounds. 

Molecular weight M - The ratio of the average mass per molecule or specified entity of a substance to 1/12 of the mass of nuclide Also called relative molar (or molecular) mass. 

Bainbridge and Jordan determined the mass of nuclides to six significant figures, the first accurate mass application. 

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