AQA AS LEVEL CHEMISTRY PAPER 1 LATEST 2025 WITH QUESTIONS
AND CORRECT VERIFIED ANSWERS GRADED A+ GUARANTEED PASS
Define mass number (A). [1] - CORRECT ANSWERS-The number of protons and neutrons
combined in an atom
Define isotope. [1] - CORRECT ANSWERS-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] - CORRECT
ANSWERS--Same chemical properties.
-As same electron configuration.
State the uses of mass spectrometry: [4] - CORRECT ANSWERS-- Identify elements
- Determine relative molecular mass.
- Determine isotopic mass.
- Determine relative abundance of isotopes.
Why is mass spectrometry done in a vacuum? [1] - CORRECT ANSWERS-Prevent positive ions
from colliding with molecules in the air.
Describe electrospray ionisation: [4] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-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] - CORRECT ANSWERS-- Each peak
represents different isotope.
- Height gives relative abundance of each isotope.
Give the formula for relative atomic mass: [1] - CORRECT ANSWERS-(sum of abundances not
100)
Describe where electrons are found. [3] - CORRECT ANSWERS-- Found in shells, orbiting
nucleus.
- Within each shell there are sub-shells.
- Within each sub-shell we find orbitals.
Define orbital. [1] - CORRECT ANSWERS-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] - CORRECT ANSWERS-a) one s orbital
b) three p orbitals
c) five d orbitals
Define highest energy electron. [1] - CORRECT ANSWERS-The outer most electron on an atom
or ion.
What is stated by the Aufbau principle? [1] - CORRECT ANSWERS-Orbitals of lower energy are
always filled first.
What are the exceptions to the Aufbau principle? [3] - CORRECT ANSWERS-Cr - 3d5 4s2
Cu - 3d10 4s1
Define ionisation energy. [2] - CORRECT ANSWERS-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] - CORRECT ANSWERS-The second
electron is removed from an ion that already has a positive charge.
Give the equation for 3rd ionisation energy. [1] - CORRECT ANSWERS-
State 3 factors affecting ionisation energy: [3] - CORRECT ANSWERS-- Atomic Radius
- Nuclear Charge
- Shielding
Explain how atomic radius affects ionisation energy. [2] - CORRECT ANSWERS-- How far the
outer electrons are from the attractive power of the nucleus.
- The further an outer electron from the attractive power of the nucleus, the less energy is required to
ionise it.
AND CORRECT VERIFIED ANSWERS GRADED A+ GUARANTEED PASS
Define mass number (A). [1] - CORRECT ANSWERS-The number of protons and neutrons
combined in an atom
Define isotope. [1] - CORRECT ANSWERS-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] - CORRECT
ANSWERS--Same chemical properties.
-As same electron configuration.
State the uses of mass spectrometry: [4] - CORRECT ANSWERS-- Identify elements
- Determine relative molecular mass.
- Determine isotopic mass.
- Determine relative abundance of isotopes.
Why is mass spectrometry done in a vacuum? [1] - CORRECT ANSWERS-Prevent positive ions
from colliding with molecules in the air.
Describe electrospray ionisation: [4] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-- 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] - CORRECT ANSWERS-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] - CORRECT ANSWERS-- Each peak
represents different isotope.
- Height gives relative abundance of each isotope.
Give the formula for relative atomic mass: [1] - CORRECT ANSWERS-(sum of abundances not
100)
Describe where electrons are found. [3] - CORRECT ANSWERS-- Found in shells, orbiting
nucleus.
- Within each shell there are sub-shells.
- Within each sub-shell we find orbitals.
Define orbital. [1] - CORRECT ANSWERS-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] - CORRECT ANSWERS-a) one s orbital
b) three p orbitals
c) five d orbitals
Define highest energy electron. [1] - CORRECT ANSWERS-The outer most electron on an atom
or ion.
What is stated by the Aufbau principle? [1] - CORRECT ANSWERS-Orbitals of lower energy are
always filled first.
What are the exceptions to the Aufbau principle? [3] - CORRECT ANSWERS-Cr - 3d5 4s2
Cu - 3d10 4s1
Define ionisation energy. [2] - CORRECT ANSWERS-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] - CORRECT ANSWERS-The second
electron is removed from an ion that already has a positive charge.
Give the equation for 3rd ionisation energy. [1] - CORRECT ANSWERS-
State 3 factors affecting ionisation energy: [3] - CORRECT ANSWERS-- Atomic Radius
- Nuclear Charge
- Shielding
Explain how atomic radius affects ionisation energy. [2] - CORRECT ANSWERS-- How far the
outer electrons are from the attractive power of the nucleus.
- The further an outer electron from the attractive power of the nucleus, the less energy is required to
ionise it.
