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CHEMISTRY U4 AOS1 > Mass spectrometry > Flashcards

Flashcards in Mass spectrometry Deck (10):
1

this technique tells us

molar mass of a compound

2

describe how fragmentation occurs.

in the ionisation chamber, high energy electrons dislodge one electron from the molecule forming the molecular ion.
M + e- -> [M]+ + 2e-
Molecular ion is unstable because only one electron is unpaired, so it breaks into fragment ions, one of which is charged.

3

name of the graph?

mass spectrum

4

define: molecular ion

formed when the entire molecule loses an electron

5

describe m/z ratio of the molecular ion

charge is one, mass is its molar mass, hence m/z ratio is the molar mass

6

define: fragment ions

forms when molecular ion splits due to its instaility

7

define: base peak

produced by most abundant ion - relative intensity set to 100%, other relative intensities are compared to it

8

what isotopes do we need to watch out for

79Br and 81Br
35Cl and 37Cl
CHO isotopes arent anywhere near as abundant.

9

what happens to 79Br and 81Br, 35Cl and 37Cl isotopes

have different molar masses os form peaks.

10

molecular ions for CH2Br2

[CH279Br2]+, [CH281Br2]+, [CH279Br81Br]+