mass defect


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mass defect

Chemistry
The difference in the mass of a polyatomic molecule and the sum of the masses of its constituent particles—i.e., electrons, protons and neutrons. The mass defect occurs because matter is converted into energy (as per Einstein’s E = mc2), which is the energy that binds the nucleus together and overcomes the mutual repulsion between protons.

Instrumentation
In mass spectrometry, mass defect refers to the positive or negative difference between an ion’s exact mass and the nearest integer.
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References in periodicals archive ?
The term "mass defect" originates from the fact that only the carbon isotope--[sup.12]C--has an integer value for its atomic weight (12 or 12.0000 to be precise).
MMDF improves upon the MDF method by allowing the user to combine the results from up to six different mass defect filters.
(vi) [DELTA]E = A[c.sup.2][DELTA]m is useful in explaining the binding energy (2.2244MeV or 3.55904 x [10.sup.-13] J), mass defect (0.002388 amu or 2.388 x [10.sup.-3] amu) and universal equality of mass of nucleons ([m.sub.n] = 1.008664 amu, [m.sub.p] = 1.006082 amu).