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The mass-to-charge ratio (m/Q) is a physical quantity relating the mass (quantity of matter) and the electric charge of a given particle, expressed in units of kilograms per coulomb (kg/C). It is most widely used in the electrodynamics of charged particles , e.g. in electron optics and ion optics .
[1] [2] Mass spectra is a plot of relative abundance against mass-to-charge ratio. It is commonly used for the identification of organic compounds from electron ionization mass spectrometry. [3] [4] Organic chemists obtain mass spectra of chemical compounds as part of structure elucidation and the analysis is part of many organic chemistry ...
atomic weight – See: relative atomic mass [11] and relative atomic mass (atomic weight) – The ratio of the average mass of the atom to the unified atomic mass unit. [12] Here the "unified atomic mass unit" refers to 1/12 of the mass of an atom of 12 C in its ground state. [13] The IUPAC definition [1] of relative atomic mass is:
Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a mass spectrum, a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures.
The Kendrick mass is used to aid in the identification of molecules of similar chemical structure from peaks in mass spectra. [16] [17] The method of stating mass was suggested in 1963 by the chemist Edward Kendrick. According to the procedure outlined by Kendrick, the mass of CH 2 is defined as 14.000 Da, instead of 14.01565 Da. [18] [19]
The molar mass of atoms of an element is given by the relative atomic mass of the element multiplied by the molar mass constant, M u ≈ 1.000 000 × 10 −3 kg/mol ≈ 1 g/mol. For normal samples from Earth with typical isotope composition, the atomic weight can be approximated by the standard atomic weight [ 2 ] or the conventional atomic weight.
In physics, the proton-to-electron mass ratio (symbol μ or β) is the rest mass of the proton (a baryon found in atoms) divided by that of the electron (a lepton found in atoms), a dimensionless quantity, namely: μ = m p /m e = 1 836.152 673 426 (32). [1]
The rms charge radius is a measure of the size of an atomic nucleus, particularly the proton distribution. The proton radius is about one femtometre = 10 −15 metre. It can be measured by the scattering of electrons by the nucleus. Relative changes in the mean squared nuclear charge distribution can be precisely measured with atomic spectroscopy.