Even-electron rule

Term · Chemistry · MLC-T-CHM-013086

A principle in mass spectrometry predicting that ions with an even number of electrons, such as protonated molecules, will fragment to produce other even-electron product ions. Conversely, odd-electron ions, like the molecular radical cations formed in electron ionization, fragment into an even-electron ion and a radical or another odd-electron ion. This rule provides a basis for interpreting fragmentation patterns and deducing the structure of the original molecule from its mass spectrum.

Table 1. Record
Identifier	MLC-T-CHM-013086
Field	Chemistry
Subject	Analytical Chemistry
References	PAC, 2013, 85, 1515. 'Definitions of terms relating to mass spectrometry (IUPAC Recommendations 2013)' on page 1542 (https://doi.org/10.1351/PAC-REC-06-04-06)

Record as JSON

{
  "id": "MLC-T-CHM-013086",
  "term": "Even-electron rule",
  "field": "Chemistry",
  "definition": "A principle in mass spectrometry predicting that ions with an even number of electrons, such as protonated molecules, will fragment to produce other even-electron product ions. Conversely, odd-electron ions, like the molecular radical cations formed in electron ionization, fragment into an even-electron ion and a radical or another odd-electron ion. This rule provides a basis for interpreting fragmentation patterns and deducing the structure of the original molecule from its mass spectrum.",
  "subject": "Analytical Chemistry",
  "references": [
    "PAC, 2013, 85, 1515. 'Definitions of terms relating to mass spectrometry (IUPAC Recommendations 2013)' on page 1542 (https://doi.org/10.1351/PAC-REC-06-04-06)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/even-electron-rule/"
}

Record 4,382 of 13,676 in Chemistry terminology (MLC-0109). Request the full dataset.