AQA A LEVEL CHEMISTRY PAPER 1
TOF steps - Correct Answers-1) ionisation
2) acceleration
3) ion drift
4) detection
5) analysis
Electron impact - Correct Answers-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 - Correct Answers-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) - Correct Answers-positive ions accelerated using electric field so they all
have the same kinetic energy
Ion drift (TOF) - Correct Answers-particles with small mass have larger velocity do ions start to
separate with lightest ions reaching detector first
Detection (TOF) - Correct Answers-positive ions hit negatively charged plate and gain an
electron which forms a current, the larger the current the higher the abundance
Analysis (TOF) - Correct Answers--computer uses data to produce mass spectrum which shows
mass m / charge z ratio
-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 - Correct Answers-Property of electron (CW or ACW)
Represented by up and down arrows
Orbitals - Correct Answers-Defined regions of space around nucleus where electrons most likely
to be found, each orbital holds 2 electrons
, Hund's Rule - Correct Answers-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 - Correct Answers-1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10
exceptions to electron configuration - Correct Answers-chromium and copper, only take one
electron in 4s orbital
Why does ionization energy decrease down a group? - Correct Answers-Atoms get bigger so
electrons further away from nucleus, greater shielding
Why does ionization energy increase across a period? - Correct Answers-Atoms get smaller,
nuclear charge increases, similar shielding
Dip in ionisation energy groups 2-3 - Correct Answers-Electrons take up higher orbital (s to p)
which makes ionisation energy lower as higher orbitals have higher energy
Dip in ionisation energy groups 5-6 - Correct Answers-Electron- electron repulsion in orbital
makes electron easier to lose
Relative atomic mass - Correct Answers-The average mass of an atom of an element/ 1/12th of
the mass of an atom of carbon-12
Empirical formula - Correct Answers-The simplest whole number ratio of atoms of each
element present in a compound
Percentage yield - Correct Answers-actual yield/theoretical yield x 100
Atom economy - Correct Answers-(Molecular mass of desired products/ Molecular mass of all
products) x 100
Electronegativity - Correct Answers-The power of an atom to attract electron density in a
covalent bond towards itself
electronegativity trend - Correct Answers-increases across a period, decreases down a group
Enthalpy change - Correct Answers-Heat energy change measured at constant pressure
Hess's Law - Correct Answers-The Enthalpy Change for a chemical reaction is independent of
the route taken
TOF steps - Correct Answers-1) ionisation
2) acceleration
3) ion drift
4) detection
5) analysis
Electron impact - Correct Answers-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 - Correct Answers-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) - Correct Answers-positive ions accelerated using electric field so they all
have the same kinetic energy
Ion drift (TOF) - Correct Answers-particles with small mass have larger velocity do ions start to
separate with lightest ions reaching detector first
Detection (TOF) - Correct Answers-positive ions hit negatively charged plate and gain an
electron which forms a current, the larger the current the higher the abundance
Analysis (TOF) - Correct Answers--computer uses data to produce mass spectrum which shows
mass m / charge z ratio
-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 - Correct Answers-Property of electron (CW or ACW)
Represented by up and down arrows
Orbitals - Correct Answers-Defined regions of space around nucleus where electrons most likely
to be found, each orbital holds 2 electrons
, Hund's Rule - Correct Answers-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 - Correct Answers-1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10
exceptions to electron configuration - Correct Answers-chromium and copper, only take one
electron in 4s orbital
Why does ionization energy decrease down a group? - Correct Answers-Atoms get bigger so
electrons further away from nucleus, greater shielding
Why does ionization energy increase across a period? - Correct Answers-Atoms get smaller,
nuclear charge increases, similar shielding
Dip in ionisation energy groups 2-3 - Correct Answers-Electrons take up higher orbital (s to p)
which makes ionisation energy lower as higher orbitals have higher energy
Dip in ionisation energy groups 5-6 - Correct Answers-Electron- electron repulsion in orbital
makes electron easier to lose
Relative atomic mass - Correct Answers-The average mass of an atom of an element/ 1/12th of
the mass of an atom of carbon-12
Empirical formula - Correct Answers-The simplest whole number ratio of atoms of each
element present in a compound
Percentage yield - Correct Answers-actual yield/theoretical yield x 100
Atom economy - Correct Answers-(Molecular mass of desired products/ Molecular mass of all
products) x 100
Electronegativity - Correct Answers-The power of an atom to attract electron density in a
covalent bond towards itself
electronegativity trend - Correct Answers-increases across a period, decreases down a group
Enthalpy change - Correct Answers-Heat energy change measured at constant pressure
Hess's Law - Correct Answers-The Enthalpy Change for a chemical reaction is independent of
the route taken
