mass defect

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Related to mass defects: mass deficiency

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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