AQA A LEVEL CHEMISTRY PAPER 1
rated A
TOF steps - 1) ionisation
2) acceleration
3) ion drift
4) detection
5) analysis
Electron impact - Sample vaporised and electron gun fires high energy electrons at it which knock off 1
electron from each particle, making them 1+ ions
NB- can knock off more than one e or break molecular ion
electrospray ionization - Sample dissolved in volatile solvent then injected through needle to give fine
mist which is attached to positive end of high voltage power supply, particles gain proton
NB- Mr of substance is actually one less than shown due to extra H+
Acceleration (TOF) - positive ions accelerated using electric field so they all have the same kinetic energy
Ion drift (TOF) - particles with small mass have larger velocity do ions start to separate with lightest ions
reaching detector first
Detection (TOF) - positive ions hit negatively charged plate and gain an electron which forms a current,
the larger the current the higher the abundance
Analysis (TOF) - -computer uses data to produce mass spectrum which shows mass m / charge z ratio
, AQA A LEVEL CHEMISTRY PAPER 1
rated A
-mr or ar is furthest right peak (small peaks larger than mr are due to isotopes)
-may be large peaks at lower mr due to fragmentation
Electron spin - Property of electron (CW or ACW)
Represented by up and down arrows
Orbitals - Defined regions of space around nucleus where electrons most likely to be found, each orbital
holds 2 electrons
Hund's Rule - Electrons prefer to occupy orbitals on their own and only pair up when no empty or bait
ask of same energy are available
Electron configuration - 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10
exceptions to electron configuration - chromium and copper, only take one electron in 4s orbital
Why does ionization energy decrease down a group? - Atoms get bigger so electrons further away from
nucleus, greater shielding
Why does ionization energy increase across a period? - Atoms get smaller, nuclear charge increases,
similar shielding
rated A
TOF steps - 1) ionisation
2) acceleration
3) ion drift
4) detection
5) analysis
Electron impact - Sample vaporised and electron gun fires high energy electrons at it which knock off 1
electron from each particle, making them 1+ ions
NB- can knock off more than one e or break molecular ion
electrospray ionization - Sample dissolved in volatile solvent then injected through needle to give fine
mist which is attached to positive end of high voltage power supply, particles gain proton
NB- Mr of substance is actually one less than shown due to extra H+
Acceleration (TOF) - positive ions accelerated using electric field so they all have the same kinetic energy
Ion drift (TOF) - particles with small mass have larger velocity do ions start to separate with lightest ions
reaching detector first
Detection (TOF) - positive ions hit negatively charged plate and gain an electron which forms a current,
the larger the current the higher the abundance
Analysis (TOF) - -computer uses data to produce mass spectrum which shows mass m / charge z ratio
, AQA A LEVEL CHEMISTRY PAPER 1
rated A
-mr or ar is furthest right peak (small peaks larger than mr are due to isotopes)
-may be large peaks at lower mr due to fragmentation
Electron spin - Property of electron (CW or ACW)
Represented by up and down arrows
Orbitals - Defined regions of space around nucleus where electrons most likely to be found, each orbital
holds 2 electrons
Hund's Rule - Electrons prefer to occupy orbitals on their own and only pair up when no empty or bait
ask of same energy are available
Electron configuration - 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10
exceptions to electron configuration - chromium and copper, only take one electron in 4s orbital
Why does ionization energy decrease down a group? - Atoms get bigger so electrons further away from
nucleus, greater shielding
Why does ionization energy increase across a period? - Atoms get smaller, nuclear charge increases,
similar shielding
