Mass, electronic energy equivalent

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... 

Of course, Eq. (3) is valid for any particle. The question is Why is the speed of the photon there One may conjecture with DiMarzio [26] that there is a more fundamental meaning for c. In this context, Munera [27] explored the possibility of deriving the main predictions of STR from Newton s theory plus a postulate of mass-energy equivalence E = mK2. The value of the unknown constant K was obtained from the acceleration of electrons [28]. The numerical value is c within the limits of accuracy of the (large) experimental error. 

The mass of an atom is generally not equal to the sum of the masses of its component protons, neutrons, and electrons. If we could imagine a reaction in which free protons, neutrons, and electrons combine to form an atom, we would find that the mass of the atom is slightly less than the total mass of the component particles (an exception is H as there is only 1 nuclear part, the proton). Further, a tremendous amount of energy is released during the reaction which produces the atom. The loss in mass is exactly equivalent to the released energy, according to Einstein s famous equation,... 

The calculated gain of energy equivalent to the loss of mass is called the binding energy of the atom (or nucleus, if it is being considered independently of the electrons in the shells). When the binding energy calculations are... 

It is also worth noting that the equivalence [317], which exists for thermal systems in terms of level of approximation and assumption between the RRKM and Slater [772] approaches, is lost in mass spectrometry. To adopt the Slater position that there is no energy flow among modes, immediately demands further information, and almost certainly further assumptions, since the form of the initial distribution of vibrational (and electronic) energy is a specific property of the ion dependent upon the ionization process. 

This set of equations connects Planck s photon energy Ep with Einstein s mass/en-ergy equivalence, with Boltzmann s kinetic energy, with the kinetic energy of a particle and with the kinetic energy of an electron in an electric field of a voltage U of 1 V. The most important conversion factors used in photochemistry and photophysics are collected in Tab. 3-2. 

From a quantitative point of view, the high abundance of undissociated HeH+ ions measured in the mass spectrometer shows conclusively that the excitation of the daughter ions through the orbital electron shaking is a relatively inefficient mechanism in the decay of this simple molecule. The high stability of the HeH" molecular ion is not surprising, since it is electronically almost equivalent to the HeH+ ion, observed in the mass spectrometer since the early 1920 s, and which has been the subject of many theoretical calculations as the most simple two-electron heteronuclear molecule. Its dissociation energy, calculated by several... 

A common practice among scientists reflects the relationship between mass and energy They express the mass of a particle in either traditional units (grams, for example) or the energy equivalent of that mass. For example, the mass of an electron can be expressed as 9.042 x 10 28 g or as 0.511 MeV. Similarly, the mass of a proton can be expressed either as 1.660 x 10 24 g or as 938.26 MeV, the energy equivalent of that mass. 

Conditions in the universe almost immediately after the big bang were not favorable for the formation of electrons. At that point in time, gamma rays, photons, and neutrinos had very large amounts of energy, much more than was needed to produce electrons. Instead, conditions favored the creation of much more massive particles with large energy equivalents. Among these particles were the muon and the proton. A muon (also known as a mu meson) is a much more massive relative of the electron. It has amass of 1.870 x 10"25 g, about 2,000 times that of an electron. A proton is even heavier, with a mass of about 1.660 x 10 24 g, nearly 3,000 times that of an electron. 

Combining Einstein s famous equation for the quantity of energy equivalent to a given amount of mass E = mc ) with the equation for the energy of a photon (E = hv = hclk), de Broglie derived an equation for the wavelength of any particle of mass m—whether planet, baseball, or electron—moving at speed u ... 

A particularly useful factor converts a given mass defect in atomic mass units to its energy equivalent in electron volts ... 

Positron emission occurs only when the energy difference between the parent radionuclide and the products exceeds 1.02 MeV (the energy equivalent of the sum of the masses of an electron and a positron). The atom s recoil, as for beta-particle emission, is a few electron volts. At lesser energy differences, a proton in the nucleus can be converted to a neutron by electron capture, i.e., the capture by the nucleus of an atomic electron from, most probably, an inner electron shell (see discussion below of CEs). The process of electron capture parallels positron emission and may occur in the same isotope. It is accompanied by emission of a neutrino and characteristic X rays due to the rearrangement of atomic electrons. Electron capture may also be signaled by the subsequent emission of gamma rays. Examples of these decays are given in Sections 9.3.4 and 9.3.6. 

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