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- 1what is used to measure Relative mass of isotopeamass spectrometer
- 21. whydoes the TIF occur in a vacuumso no other particles can interfere with the experiment
- 3ionisation Electron impact and electrospray ionisationElectron Impact
- high energy electrons in an electron gun fired towards a sample and knocks of an e-
X(g)-----> X+(g) + e-
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ELECTROSPRAY IONISATION -sample dissolved in volatile polar solvent
- injected through a needle at a high voltage and becomes positive by gaining a proton
X(g) + H+ ----->XH+ (g) - 4acceleration+ ion are accelerated by an electric field to a constant KE
(VELOCITY DEPENDS ON - mass of the ion)
more mass - lower velocity while less mass =higher v
KE=1/2mv2 - 53. ION DRIFT/ FLIGHTions separate at this stage (all ions have a constant KE)
IONS are allowed to DIFT along a flight tub of a known distance and TIME TAKEN FOR ION TO REACH DETECTOR IS MEASURED - 6TOF depends on on velocity which depends on the mass of the ionions with lower mass take shorter time to reach detector
MASS OF ION - can be determined from time taken for the ion to reach he detector - 74. ION DETECTION+ ion hits detector(- charged plate) and picks AN ELECTRON(current is generated when ions gain and electron)
- 8the greater the abundance of ions hitting the platethe bigger the current produced
- 95. DATA ANALYSISdetection linked to amplifier then to a recorder (CONVERTS CURRENT INTO A PEAK)- displayed on mass spectrum
- 10the height of peak is proportional tothe size of the current generated and therefore proportional to the abundace of that ion
- 11what is the peak displayed ona plot of abundance/ (M/Z)
(m/z is the same as mass as +1 charge is produced) - 12Ar calculationm/z of peak x abundance of that peak/ abundances
- 13fragmentationcovalently bonded molecules have thier bonds broken and break into fragments during electron impact ionisation by the elctron gun
- 14fragmentation doesn't occur to all moleculessome remain intact and just gains a + charge ( unfragmented and + charged molecules will give the peak with the greatest m/z value
(the peak tells us the MR of the molecule) - 15very little fragmentation occurs on electrospray ionisation meaning...less peaks in a mass spectrum
sample = peak with greatesr m/z value - 1 - 16Mr IS FURTHEST RIGHT79 Br - 81Br --- 1;1
35Cl - 37 cl--- 3;1 - 172 Cl - 9;6;12 Br- 1:2:1
- 18electrons are arranged inElectrons shells (principle energy levels) which themselves have (sub-levels)
SUBLEVELS _ spdf (increase in energy) - 19sublevels are further divided into orbitalseach orbital holds a maximum of 2 electrons
direction of arrows - represent spin of e-
pared electrons have OPPOSSITE SPIN (reduces extra repulsion between paired electrons)
E- OCCUPY ORBITALS AS UNPAIRED E- RATHER THAN PARED UNTIL THEY HAVE TO BE PAIRED UP - 20why does 4s fills before 3dit is lower in energy
BUR WHEN ATOMS ARE IONISED e- are removed from 4s before 3d (furthest from nucleus) - 21exceptions and reasonsCr and CU doesn't follow the rules
Cr- half filled subshell (more stable)
Cu - full subshell - more stable (energetically favourable)
MORE STABLE ARRANGEMENTS - 22FIRST IONISATION ENERGYminimum amount of energy needed to remove a mole of e- from one mole of gaseous atom
- 23successive IEas more e- are removed from an atom the amount of energy needed to remove the next e- from an increasingly + ato will always increase - BECAUSE STRENGTH BETWEEN THE NUCLEAUS AND OUTER ELECTRON INCREASES AS ANOTHER E- IS REMOVED (causes decrease in atomic radius and e- is removed from closer to he nucleus)
- 24successive Ie is used tofind the group in which an element belongs (there will always be a very large increase in IE when an electron is removed from a new principle energy level that is much closer to the nucleus)
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- A level Chemistry A level Fichas sobre AS, creado por Ellaine Wahome el 29/10/2022.
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- Ellaine Wahome
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