The Mass Defect

We have known for most of the 20 century that mass and energy are interconvertible. The traditional mass and energy conservation laws have been combined to state that the total quantity of mass-energy in the universe is constant. Therefore, when any reacting system releases or absorbs energy, there must be an accompanying loss or gain in mass. 

This relation between mass and energy is not important for chemical reactions because the energy changes involved in breaking or forming bonds are so small that the mass changes are negligible. When 1 mol of water breaks up into its atoms, for example, heat is absorbed  

We find the mass that is equivalent to this energy from Einstein s equation  

The mass of one C atom is 12 amu (exactly). The difference in mass (Am) is the total mass of the nucleons minus the mass of the nucleus  

Note that the mass of the nucleus is less than the combined masses of its nucleons. The mass decrease that occurs when nucleons are united into a nucleus is called the mass defect. The size of this mass change (9.89X10 g/mol) is nearly 10 million times that of the previous bond breakage (10.4X10 g/mol) and is easily observed on any laboratory balance. 

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High-mass resolution is needed to separate mass interferences of molecular and atom ions. Because of the mass defect of the binding energy of the nucleus, atomic ions have a slightly smaller mass than the corresponding molecular ions. To observe this typical mass resolutions between 5000 and 10000 are necessary. 

The quantity just calculated is referred to as the mass defect. The corresponding energy difference is... 

Beta radiation Electron emission from unstable nuclei, 26,30,528 Binary molecular compound, 41-42,190 Binding energy Energy equivalent of the mass defect measure of nuclear stability, 522,523 Bismuth (m) sulfide, 540 Blassie, Michael, 629 Blind staggers, 574 Blister copper, 539 Blood alcohol concentrations, 43t Body-centered cubic cell (BCC) A cubic unit cell with an atom at each comer and one at the center, 246 Bohrmodd Model of the hydrogen atom... 

Because an increase in resolution causes a decrease in sensitivity, it is best to operate at the lowest resolution commensurate with good results. Some instrument data systems will allow calibration with an external reference material such as perfluorokerosene and then use of a secondary reference material for the internal mass reference. Tetraiodothiophene, vaporized using the solids probe inlet, is recommended as the secondary reference. The accurate masses are 79.9721, 127.9045, 162.9045, 206.8765, 253.8090, 293.7950, 333.7810, 460.6855, and 587.5900. For a higher mass standard, use hexaiodobenzene. Because the mass defect for these internal reference ions are so large, a resolution of 2000 is ample to separate these ions from almost any sample ions encountered in GC/MS. 

The mass defect is the difference between the total mass of all products and the total mass of all reactants ... 

The isotopic molar masses are precise to five or more significant figures, so we are tempted to express the result with five significant figures. The mass defect is determined by addition and subtraction, however, and two of the isotopic molar masses are known to just three decimal places, so the mass defect is precise to three decimal places, and the... 

The left-hand sides of Eqs. (A 1.69) and (A 1.70) are of the same form, which enables the perturbed GF with the mass defect Am to be readily expressed in terms of the unperturbed one ... 

This graph and Fig. 26-6 are almost the inverse of one another, with the maxima of one being the minima of the other. Actual nuclidic mass is often a number slightly less than the number of nucleons (mass number). This difference divided by the number of nucleons (packing fraction) is proportional to the negative of the mass defect per nucleon. 

The isotope-coded affinity tag approach utilizes chemical labeling that allows quantitation when combined with mass spectrometry. ICAT is desirable because the chemical labeling takes advantage of the mass defects of monoisotopic stable isotopes. ICAT uses an ICAT reagent to differentially label protein samples on their cysteine residues. ICAT is advantageous because it permits the evaluation of low-abundance proteins and proteins at both extremes of molecular weights and isoelectric points.60... 

We make the observation that, contrary to naive expectations of the mass defect as a result of the binding energy from Cooper pairing [16], AM c2... 

Figure 5. Hot (T = 40 MeV) versus cold (T = 0) quark star configurations for the Gaussian model(Left graphic)and Lorentzian(Right graphic) case A with diquark condensation (dashed versus full lines) and case B without diquark condensation (dash-dash-dotted versus dash-dotted lines). When a quark star with initial mass Mi cools down from T = 40 MeV to T = 0 at fixed baryon number Nb the mass defect AM occurs.

A mass defect of about 0.1 M occurs in the cooling of a hot configuration to a cold one already without diquark condensation. It is mainly determined by the change of the configuration due to changes in the EoS. Cooling the star with diquark condensation results even in a lowering of the mass defect contrary to naive expectations. 

A reference configuration with total baryon number Ni> = 1.51 Nq (where Nq is the total baryon number of the sun) is chosen and the case with (configurations A and B in Fig. 13) and without antineutrinos (/ in Fig. 13) are compared. A mass defect can be calculated between the configurations with trapped antineutrinos and without it at a constant total baryon number and the result is shown in Fig. 14). The mass defect could be interpreted as an energy release if the configurations A, B with antineutrinos are initial states and the configuration / without them is the final state of a protoneutron star evolution. 

When 1 mol of U-238 decays to Th-234, 5 X 10 kg of matter is converted to energy (the mass defect). Calculate the amount of energy released. 

The mass defect for helium-4 is 0.0304 g/mol. Determine the nuclear binding energy in joules per mole for 1 mol of helium-4. 

The difference in mass is significant. It would show up on any reasonably precise balance. Thus, the mass of the nucleus of carbon-12 is significantly less than the mass of its component nucleons. The difference in mass between a nucleus and its nucleons is known as the mass defect. What causes this mass defect It is caused by the nuclear binding energy the energy associated with the strong force that holds a nucleus together. 

The difference between the exact mass of an atom molecule, ion and its integer mass in MS. In physics, the mass defect represents the difference between the mass of an atom and the sum of the masses of its unbound constituents. 

From nuclear physics it is known that the mass of a nucleus is always less than the sum of the masses of its components, the protons and neutrons. This phenomenon - called the mass defect (Am) - seems to be in conflict with the law of conservation of mass. The mass defect Am can be calculated by comparing the atomic weight of the nucleus mk with the sum of the masses of the protons nip and neutrons mn ... 

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