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Atomic structure
- Sub-atomic particles
- Electrons
- Charge- -1
- Mass- Neglidgible
- no. of electrons in shell = 2n^2
- Charge- -1
- Nucleons
- Protons
- Mass- 1
- Charge- +1
- Mass- 1
- Neutrons
- Charge- 0
- Mass- 1
- Charge- 0
- Protons
- Electrons
- Atoms
- Mass no.- protons+neutrons
- Atomic no.- protons
- Isotope- Same no. of protons,
different no. of neutrons
- Mass no.- protons+neutrons
- Mass spectroscopy
- Vacuum so that ions do not
collide with air molecules
- Gaseous sample
- Ionisation
- Beam of electrons knocks out an
electron (+ion formed)
- Sometimes 2 elections
knocked out (halves the m/z)
- Sometimes 2 elections
knocked out (halves the m/z)
- Beam of electrons knocks out an
electron (+ion formed)
- Acceleration
- Positive ions attracted to
negatively charged plates
- The speed they go
depends on the mass
- Some pass through slits in
the plate, forming an ion beam
- Some pass through slits in
the plate, forming an ion beam
- The speed they go
depends on the mass
- Positive ions attracted to
negatively charged plates
- Deflection
- Beam of ions move into
magnetic field at right
angles to its direction of
travel
- Magnetic field deflects the
ions into an arc of a circle
- Magnetic field deflects the
ions into an arc of a circle
- Deflection depends on
- m/z ratio
- 2+ ions deflected twice as much
as 1+ ions with the same mass
- EMF strength
- m/z ratio
- Beam of ions move into
magnetic field at right
angles to its direction of
travel
- Detection
- EMF gradually increased
so ions of increasing mass
enter the detector
- Ions accept electrons when they
strike the detector, so lose charge
- creates a current that is proportional to
the abundance of each ion
- creates a current that is proportional to
the abundance of each ion
- Ions accept electrons when they
strike the detector, so lose charge
- EMF gradually increased
so ions of increasing mass
enter the detector
- Results
- From the strength of the EMF at which an
ion hits the detector, a computer works out
the m/z ratio of the original ion
- Mass spectrum produced
- Isotopes
- Average relative atomic mass = Σ(abundance x m/z) ÷ overall abundance
- Average relative atomic mass = Σ(abundance x m/z) ÷ overall abundance
- Molecular ions e.g. Cl2
- Isotopes
- Mass spectrum produced
- From the strength of the EMF at which an
ion hits the detector, a computer works out
the m/z ratio of the original ion
- Vacuum so that ions do not
collide with air molecules
- Electron arrangement
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10 4f14
- Add 4s before 3d
- Remove 4s before 3d
- When a full orbital, electron spin =0
- When in a new sub level, each orbital
is singly filled before being doubly
filled
- Add 4s before 3d
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10 4f14
- Electron arrangement and ionisation energy
- The energy required to remove one mole of electrons from one
mole of gaseous atoms
- Each ionisation requires more energy than the prior one
(successive ionisation energies)
- Depending on how close each ionisation
energy is, it shows how many electrons
are in a shell
- Depending on how close each ionisation
energy is, it shows how many electrons
are in a shell
- Each ionisation requires more energy than the prior one
(successive ionisation energies)
- The energy required to remove one mole of electrons from one
mole of gaseous atoms
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