AQA A Level Chemistry June 2025 Paper 1
Question Paper [VERIFIED] Q Q
Describe the nuclear model of an atom. [2] - - Nucleus containing of protons and neutrons.
- Surrounded by electrons in energy levels.
State the relative mass and charges of a proton [2]. - Mass: 1
Charge: +1
State the relative mass and charges of a neutron. [2] - Mass: 1
Charge: 0
Define atomic number (Z). [1] - The number of protons in an atom.
State the relative mass and charges of an electron. [2] - Mass: 1/1840
Charge: -1
Define mass number (A). [1] - The number of protons and neutrons combined in an atom
Define isotope. [1] - Atoms with the same number of protons but a different number of neutrons.
Describe the chemical properties of two isotopes of the same element. [2] - -Same chemical properties.
-As same electron configuration.
State the uses of mass spectrometry: [4] - - Identify elements
- Determine relative molecular mass.
- Determine isotopic mass.
- Determine relative abundance of isotopes.
,Why is mass spectrometry done in a vacuum? [1] - Prevent positive ions from colliding with molecules in
the air.
Describe electrospray ionisation: [4] - - Sample dissolved in volatile solvent.
- Injected through a fine hypodermic needle giving a fine mist/aerosol.
- Tip of needle connected to positive terminal of a high voltage.
- Each molecule gains a proton as it leaves the needle.
Describe acceleration: [2] - - The positive ions are attracted to a negatively charged plate and accelerate
towards it.
- All ions accelerate forward so that they have the same kinetic energy, but reach different velocities due
to their varying masses. (lighter → faster)
Describe ion drift: [2] - - Some of the ions pass through a hole in the negatively charged plate, forming a
beam of particles. They travel along the 'flight tube' towards the detector.
- As the ions are travelling at different speeds, they drift apart further.
Describe detection: [2] - - When the positive ions hit the negatively charged detection plate, they gain an
electron.
- This generates a current, the size of which is proportional to the number of each type of ion.
Describe data analysis: [1] - The signal from the detector is passed to a computer which generates a
mass spectrum from the current.
What does each peak on the graph represent? [2] - - Each peak represents different isotope.
- Height gives relative abundance of each isotope.
Give the formula for relative atomic mass: [1] - (sum of abundances not 100)
Describe where electrons are found. [3] - - Found in shells, orbiting nucleus.
- Within each shell there are sub-shells.
, - Within each sub-shell we find orbitals.
Define orbital. [1] - An orbital is a region within an atom that can hold up to two electrons with opposite
spins.
How many orbitals are there in...
a) an s sub-shell
b) a p sub-shell
c) a d sub-shell [3] - a) one s orbital
b) three p orbitals
c) five d orbitals
Define highest energy electron. [1] - The outer most electron on an atom or ion.
What is stated by the Aufbau principle? [1] - Orbitals of lower energy are always filled first.
What are the exceptions to the Aufbau principle? [3] - Cr - 3d5 4s2
Cu - 3d10 4s1
Define ionisation energy. [2] - The amount of energy needed to remove a mole of electrons from a mole
of atoms, in the gaseous state.
Units kJmol-1
Why does ionisation energy increase each time? [1] - The second electron is removed from an ion that
already has a positive charge.
Give the equation for 3rd ionisation energy. [1] -
State 3 factors affecting ionisation energy: [3] - - Atomic Radius
- Nuclear Charge
Question Paper [VERIFIED] Q Q
Describe the nuclear model of an atom. [2] - - Nucleus containing of protons and neutrons.
- Surrounded by electrons in energy levels.
State the relative mass and charges of a proton [2]. - Mass: 1
Charge: +1
State the relative mass and charges of a neutron. [2] - Mass: 1
Charge: 0
Define atomic number (Z). [1] - The number of protons in an atom.
State the relative mass and charges of an electron. [2] - Mass: 1/1840
Charge: -1
Define mass number (A). [1] - The number of protons and neutrons combined in an atom
Define isotope. [1] - Atoms with the same number of protons but a different number of neutrons.
Describe the chemical properties of two isotopes of the same element. [2] - -Same chemical properties.
-As same electron configuration.
State the uses of mass spectrometry: [4] - - Identify elements
- Determine relative molecular mass.
- Determine isotopic mass.
- Determine relative abundance of isotopes.
,Why is mass spectrometry done in a vacuum? [1] - Prevent positive ions from colliding with molecules in
the air.
Describe electrospray ionisation: [4] - - Sample dissolved in volatile solvent.
- Injected through a fine hypodermic needle giving a fine mist/aerosol.
- Tip of needle connected to positive terminal of a high voltage.
- Each molecule gains a proton as it leaves the needle.
Describe acceleration: [2] - - The positive ions are attracted to a negatively charged plate and accelerate
towards it.
- All ions accelerate forward so that they have the same kinetic energy, but reach different velocities due
to their varying masses. (lighter → faster)
Describe ion drift: [2] - - Some of the ions pass through a hole in the negatively charged plate, forming a
beam of particles. They travel along the 'flight tube' towards the detector.
- As the ions are travelling at different speeds, they drift apart further.
Describe detection: [2] - - When the positive ions hit the negatively charged detection plate, they gain an
electron.
- This generates a current, the size of which is proportional to the number of each type of ion.
Describe data analysis: [1] - The signal from the detector is passed to a computer which generates a
mass spectrum from the current.
What does each peak on the graph represent? [2] - - Each peak represents different isotope.
- Height gives relative abundance of each isotope.
Give the formula for relative atomic mass: [1] - (sum of abundances not 100)
Describe where electrons are found. [3] - - Found in shells, orbiting nucleus.
- Within each shell there are sub-shells.
, - Within each sub-shell we find orbitals.
Define orbital. [1] - An orbital is a region within an atom that can hold up to two electrons with opposite
spins.
How many orbitals are there in...
a) an s sub-shell
b) a p sub-shell
c) a d sub-shell [3] - a) one s orbital
b) three p orbitals
c) five d orbitals
Define highest energy electron. [1] - The outer most electron on an atom or ion.
What is stated by the Aufbau principle? [1] - Orbitals of lower energy are always filled first.
What are the exceptions to the Aufbau principle? [3] - Cr - 3d5 4s2
Cu - 3d10 4s1
Define ionisation energy. [2] - The amount of energy needed to remove a mole of electrons from a mole
of atoms, in the gaseous state.
Units kJmol-1
Why does ionisation energy increase each time? [1] - The second electron is removed from an ion that
already has a positive charge.
Give the equation for 3rd ionisation energy. [1] -
State 3 factors affecting ionisation energy: [3] - - Atomic Radius
- Nuclear Charge
