11/21 measurement and data processing
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what is IHD
index of hydrogen deficiency
formula for IHD
2
how do you deal with a nitrogen atom when calculating IHD
add one carbon atom and one hydrogen atom to the molecualr formula
how do you deal with an oxygen and sulfur atom when calculating IHD
ignore them
what does the IHD give
the number of molecuels of hydrogen needed to convert the organic compound to the corresponding saturated, non cyclic molecule.
how do you deal with a halogen atom when calculating IHD
count halogens as hydrogens (same group)
why must particles be ionised in a mass spectrometer
so they can be accelerated and deflected
describe the process of ionisation in a mass spectrometer
gaseous atoms bombarded by electrons from an electron gun and are ionised. sufficent energy is given to form ions of 1+ charge
describe the process of acceleration in a mass spectrometer
ions charged so they can be accelerated by an electric field
describe the process of deflection in a mass spectrometer
charged particels will be deflected by a magnetic or electric field
describe the process of detection in a mass spectrometer
by electric or photographic methods
heavier isotopes are detected…
less
what does the radius of the mass spectrometry path depend on
the mass/charge ratio
ions of heavier isotopes have larger…
m/z values so follow a larger radius curve.
most ions are… so the amount of seperation depends on their…
1+ charged, so depends on their mass
what are the steps of mass spectrometry
ionisation acceleration deflection adetection
what is the y axis of a mass spectrometry
relative/percentage abundance
describe the process of fragmentation
a gaseous sample compound is injected into the mass spectrometer it is bombarded by high energy electrons from an electron gun a molecular ion is produced. contains an unpaired electron so it is also a free radical produces a molecular ion. contains an unparied electron so is also a free radical
what does fragmentation produce
produces a molecular ion. contains an unparied electron so is also a free radical (ion and free radical)
what happens if a covalent bond in the molecular ion produced by mass spectrometry
fragmentation
what parts of the of the molecular ion is attracted to the charged plates in the mass spectrometer and is detected subsequently
only the ion
what can the molecular ion also undergo
fragmentation or re-arrangement to produce particles of smaller mass
the more stable the ion,
the greater the intensity of the peak
why do some elements like bromine and chlorine have different m/z values
isotope