AQA A LEVEL CHEMISTRY PAPER 1 A+GRADED……..
1. TOF steps: 1) ionisation
2) acceleration
3) ion drift
4) detection
5) analysis
2. 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
3. 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+
4. Acceleration (TOF): positive ions accelerated using electric field so they all have the same kinetic energy
5. Ion drift (TOF): particles with small mass have larger velocity do ions start to separate with lightest ions reaching
detector first
6. Detection (TOF): positive ions hit negatively charged plate and gain an electron which forms a current, the larger the
current the higher the abundance
7. Analysis (TOF): -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
8. Electron spin: Property of electron (CW or ACW)
Represented by up and down arrows
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, 9. Orbitals: Defined regions of space around nucleus where electrons most likely to be found, each orbital holds 2 electrons
10. 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
11. Electron configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10
12. exceptions to electron configuration: chromium and copper, only take one electron in 4s orbital
13. Why does ionization energy decrease down a group?: Atoms get bigger so electrons further
away from nucleus, greater shielding
14. Why does ionization energy increase across a period?: Atoms get smaller, nuclear
charge increases, similar shielding
15. Dip in ionisation energy groups 2-3: Electrons take up higher orbital (s to p) which makes
ionisation energy lower as higher orbitals have higher energy
16. Dip in ionisation energy groups 5-6: Electron- electron repulsion in orbital makes electron easier to lose
17. Relative atomic mass: The average mass of an atom of an element/ 1/12th of the mass of an atom of carbon-12
18. Empirical formula: The simplest whole number ratio of atoms of each element present in a compound
19. Percentage yield: actual yield/theoretical yield x 100
20. Atom economy: (Molecular mass of desired products/ Molecular mass of all products) x 100
21. Electronegativity: The power of an atom to attract electron density in a covalent bond towards itself
22. electronegativity trend: increases across a period, decreases down a group
23. Enthalpy change: Heat energy change measured at constant pressure
24. Hess's Law: The Enthalpy Change for a chemical reaction is independent of the route taken
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1. TOF steps: 1) ionisation
2) acceleration
3) ion drift
4) detection
5) analysis
2. 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
3. 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+
4. Acceleration (TOF): positive ions accelerated using electric field so they all have the same kinetic energy
5. Ion drift (TOF): particles with small mass have larger velocity do ions start to separate with lightest ions reaching
detector first
6. Detection (TOF): positive ions hit negatively charged plate and gain an electron which forms a current, the larger the
current the higher the abundance
7. Analysis (TOF): -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
8. Electron spin: Property of electron (CW or ACW)
Represented by up and down arrows
1/6
, 9. Orbitals: Defined regions of space around nucleus where electrons most likely to be found, each orbital holds 2 electrons
10. 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
11. Electron configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10
12. exceptions to electron configuration: chromium and copper, only take one electron in 4s orbital
13. Why does ionization energy decrease down a group?: Atoms get bigger so electrons further
away from nucleus, greater shielding
14. Why does ionization energy increase across a period?: Atoms get smaller, nuclear
charge increases, similar shielding
15. Dip in ionisation energy groups 2-3: Electrons take up higher orbital (s to p) which makes
ionisation energy lower as higher orbitals have higher energy
16. Dip in ionisation energy groups 5-6: Electron- electron repulsion in orbital makes electron easier to lose
17. Relative atomic mass: The average mass of an atom of an element/ 1/12th of the mass of an atom of carbon-12
18. Empirical formula: The simplest whole number ratio of atoms of each element present in a compound
19. Percentage yield: actual yield/theoretical yield x 100
20. Atom economy: (Molecular mass of desired products/ Molecular mass of all products) x 100
21. Electronegativity: The power of an atom to attract electron density in a covalent bond towards itself
22. electronegativity trend: increases across a period, decreases down a group
23. Enthalpy change: Heat energy change measured at constant pressure
24. Hess's Law: The Enthalpy Change for a chemical reaction is independent of the route taken
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