AQA A LEVEL CHEMISTRY PAPER 1
EXAM 2026 (Actual Exam) Questions
with verified Answers (Latest Update
2025) UPDATE!!
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
-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
OrbitalsDefined 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
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
Dip in ionisation energy groups 5-6 Electron- electron repulsion in orbital makes electron easier
to lose
Relative atomic mass The average mass of an atom of an element/ 1/12th of the mass of an atom
of carbon-12
Empirical formula The simplest whole number ratio of atoms of each element present in a
compound
Percentage yield actual yield/theoretical yield x 100
Atom economy (Molecular mass of desired products/ Molecular mass of all products) x 100
Electronegativity The power of an atom to attract electron density in a covalent bond towards
itself
electronegativity trend increases across a period, decreases down a group
Enthalpy change Heat energy change measured at constant pressure
Hess's Law The Enthalpy Change for a chemical reaction is independent of the route taken
Mean bond enthalpy Energy required to break one mole of covalent bonds between two given
atoms, averaged across a range of compounds
Activation energy the minimum energy colliding particles must have in order to react
dynamic equilibrium Forward and backward reactions take place at same rate so concentrations
of products and reactants remain constant
Only reached in closed system
Le Chatelier's Principle When a system at equilibrium is disturbed, the equilibrium shifts in the
direction that reduces the disturbance
Haber process conditions - 200 atm : high pressures favour forwards reaction but are costly
- 450°C : low temperature favours towards reaction but rate of reaction too slow at low temps
- iron catalyst
Effect of concentration on Kc no effect
Solubility of group 2 hydroxides Solubility increases down the group
Solubility if group 2 sulphates Solubility decreases down group
Use of Mg Extract titanium from its ore
EXAM 2026 (Actual Exam) Questions
with verified Answers (Latest Update
2025) UPDATE!!
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
-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
OrbitalsDefined 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
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
Dip in ionisation energy groups 5-6 Electron- electron repulsion in orbital makes electron easier
to lose
Relative atomic mass The average mass of an atom of an element/ 1/12th of the mass of an atom
of carbon-12
Empirical formula The simplest whole number ratio of atoms of each element present in a
compound
Percentage yield actual yield/theoretical yield x 100
Atom economy (Molecular mass of desired products/ Molecular mass of all products) x 100
Electronegativity The power of an atom to attract electron density in a covalent bond towards
itself
electronegativity trend increases across a period, decreases down a group
Enthalpy change Heat energy change measured at constant pressure
Hess's Law The Enthalpy Change for a chemical reaction is independent of the route taken
Mean bond enthalpy Energy required to break one mole of covalent bonds between two given
atoms, averaged across a range of compounds
Activation energy the minimum energy colliding particles must have in order to react
dynamic equilibrium Forward and backward reactions take place at same rate so concentrations
of products and reactants remain constant
Only reached in closed system
Le Chatelier's Principle When a system at equilibrium is disturbed, the equilibrium shifts in the
direction that reduces the disturbance
Haber process conditions - 200 atm : high pressures favour forwards reaction but are costly
- 450°C : low temperature favours towards reaction but rate of reaction too slow at low temps
- iron catalyst
Effect of concentration on Kc no effect
Solubility of group 2 hydroxides Solubility increases down the group
Solubility if group 2 sulphates Solubility decreases down group
Use of Mg Extract titanium from its ore
