Molecular ion: Difference between revisions
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{{DefName|An ion formed simply by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons. For molecules containing multi-isotope elements, a number of different isotopologue molecular ions will be formed. The one containing the most abundant naturally occurring isotopes of all atoms that make up the molecule is termed the monoisotopic molecular ion, whereas the others are termed isotopic molecular ions. The most abundant of these isotopologue molecular ions is sometimes termed as the top molecular ion. The mass of the molecular ion is, by definition, calculated for the monoisotopic molecular ion using therefore the masses of the most abundant isotopes with a correction for the mass of the electron(s) that has being added or removed. For instance, electron ionization of BF<sub>3</sub> gives two isotopologue ions, <sup>10</sup>B<sup>19</sup>F<sub>3</sub><sup>+.</sup> of <i>m/z</i> 67 and <sup>11</sup>B<sup>19</sup>F<sub>3</sub><sup>+.</sup> of <i>m/z</i> 68, the heavier one being the (top) monoisotopic molecular ion with a nominal mass of 68 u (Da) since <sup>11</sup>B is more abundant than <sup>10</sup>B. The lighter ion of <i>m/z</i> 67<sup>10</sup>B<sup>19</sup>F<sub>3</sub><sup>+.</sup> is an isotopic molecular ion. }} | {{DefName|An ion formed simply by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons. For molecules containing multi-isotope elements, a number of different isotopologue molecular ions will be formed. The one containing the most abundant naturally occurring isotopes of all atoms that make up the molecule is termed the monoisotopic molecular ion, whereas the others are termed isotopic molecular ions. The most abundant of these isotopologue molecular ions is sometimes termed as the top molecular ion. The mass of the molecular ion is, by definition, calculated for the monoisotopic molecular ion using therefore the masses of the most abundant isotopes with a correction for the mass of the electron(s) that has being added or removed. For instance, electron ionization of BF<sub>3</sub> gives two isotopologue ions, <sup>10</sup>B<sup>19</sup>F<sub>3</sub><sup>+.</sup> of <i>m/z</i> 67 and <sup>11</sup>B<sup>19</sup>F<sub>3</sub><sup>+.</sup> of <i>m/z</i> 68, the heavier one being the (top) monoisotopic molecular ion with a nominal mass of 68 u (Da) since <sup>11</sup>B is more abundant than <sup>10</sup>B. The lighter ion of <i>m/z</i> 67<sup>10</sup>B<sup>19</sup>F<sub>3</sub><sup>+.</sup> is an isotopic molecular ion. }} | ||
== [[Orange Book]] Entry == | |||
An ion formed by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons without fragmentation of the molecular structure. The mass of this ion corresponds to the sum of the masses of the most abundant naturally occurring isotopes of the various atoms that make up the molecule, with a correction for the masses of the electrons lost or gain. | |||
== [[Gold Book]] Entry == | |||
[http://www.nicmila.org/Gold/Output/M03988.xhtml molecular ion] | |||
An ion formed by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons without fragmentation of the molecular structure. The mass of this ion corresponds to the sum of the masses of the most abundant naturally occuring isotopes of the various atoms that make up the molecule (with a correction for the masses of the electron(s) lost or gained). For example, the mass of the molecular ion of ethyl bromide C<sub>2</sub>H<sub>5</sub> <sup>79</sup>Br will be plus 51.0078246 plus 78.91839 minus the mass of the electron (''m<sub>e</sub>''). This is equal to 107.95751 u - ''m<sub>e</sub>'', being the unified atomic mass unit based on the standard that the mass of the isotope <sup>12</sup>C = 12u exactly. | |||
[[Category:Ions]] | [[Category:Ions]] | ||
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[[Isotopologue Ion]] | [[Isotopologue Ion]] | ||
[[Isotope Cluster Ion]] | [[Isotope Cluster Ion]] | ||
[[Mass Units]] | [[Mass Units]] | ||
[[Nominal Mass]] | [[Nominal Mass]] | ||
Revision as of 01:15, 11 February 2005
| DRAFT DEFINITION |
| Molecular ion |
|---|
| An ion formed simply by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons. For molecules containing multi-isotope elements, a number of different isotopologue molecular ions will be formed. The one containing the most abundant naturally occurring isotopes of all atoms that make up the molecule is termed the monoisotopic molecular ion, whereas the others are termed isotopic molecular ions. The most abundant of these isotopologue molecular ions is sometimes termed as the top molecular ion. The mass of the molecular ion is, by definition, calculated for the monoisotopic molecular ion using therefore the masses of the most abundant isotopes with a correction for the mass of the electron(s) that has being added or removed. For instance, electron ionization of BF3 gives two isotopologue ions, 10B19F3+. of m/z 67 and 11B19F3+. of m/z 68, the heavier one being the (top) monoisotopic molecular ion with a nominal mass of 68 u (Da) since 11B is more abundant than 10B. The lighter ion of m/z 6710B19F3+. is an isotopic molecular ion. |
| Considered between 2004 and 2006 but not included in the 2006 PAC submission |
| This is an unofficial draft definition presented for information and comment. |
Orange Book Entry
An ion formed by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons without fragmentation of the molecular structure. The mass of this ion corresponds to the sum of the masses of the most abundant naturally occurring isotopes of the various atoms that make up the molecule, with a correction for the masses of the electrons lost or gain.
Gold Book Entry
An ion formed by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons without fragmentation of the molecular structure. The mass of this ion corresponds to the sum of the masses of the most abundant naturally occuring isotopes of the various atoms that make up the molecule (with a correction for the masses of the electron(s) lost or gained). For example, the mass of the molecular ion of ethyl bromide C2H5 79Br will be plus 51.0078246 plus 78.91839 minus the mass of the electron (me). This is equal to 107.95751 u - me, being the unified atomic mass unit based on the standard that the mass of the isotope 12C = 12u exactly.
