Atomic theory 2 Flashcards
upon what principle is the atomic mass spectrometer based?
that ions are separated according to their masses (mass-charge ratio when moving in a magnetic field
4 uses of the mass spectrometer
a) to identify the presence of different isotopes in a sample
b) to show that relative abundance of the isotopes of an element
c) to calculate relative atomic and molecular masses
d) it helps in identifying compounds if they come from an unknown sources
5 stages involved in the use of the mass spectrometer
vaporisation production of positive ions acceleration deflection detection
what does the mass spectrometer have that allows vaporisation to occur
it contains a vacuum
what vaporises the substance in the mass spectrometer
the high temperature
what property must the particles have to move through the mass spectrometer
they must be in the gaseous phase
3 points on explanation of vaporisation in the mass spectrometer
the substance is injected into the mass spectrometer which contains a vacuum
the high temperature vaporises the substance
to move through the machine the particles must be in a gaseous phase
how does the mass spectrometer produce positive ions ?
an ‘electron gun’ fires high-energy electrons at the vaporised substance, which causes electrons to be knocked out of orbit and thus form positive ions
how does the mass spectrometer accelerate the ions?
it contains negatively charged plates/grid that attract the positive ions and causes these positive ions to move at high speeds and concentrates the into a narrow beam
how does deflection occur in the mass spectrometer ?
the beam of positive ions is then deflected by a magnetic field. the lighter particles deflect readily, the heavier particles less readily so the ions are now being separates per their mass (and charge)
explain detection in the mass spectrometer
these particles hit against an analyser which sends different impulses to a recording device which shows up as a series of lines and peaks on a piece of paper. the resulting ‘picture’ is called a mass spectrum. the detector counts the numbers of different ions hitting against it and therefore can measure the relative abundance of each type of isotope.
where does acceleration occur in the diagram of the mass spectrometer
at the very start, just after ionisation
what is the piece of equipment at the bend of the mass spectrometer
the electromagnet
what occurs at the bend of the mass spectrometer
deflection
the label for the tube coming out of the mass spectrometer after the bend
to vacuum pump
