A LEVEL EDEXCEL CHEMISTRY
PRACTICE EXAM
SECTION 1: ATOMIC STRUCTURE & PERIODICITY
Questions 1–25
Question 1
Electronic configuration decides the chemical properties of an element (periodicity). Which
statement correctly describes s-block elements?
A) They have completely filled d subshells and are unreactive
B) They have 1 or 2 outer shell electrons, which are easily lost to form positive ions
C) They gain electrons to form negative ions with inert gas configuration
D) They share electrons to form covalent bonds exclusively
Correct answer: B
Rationale: s-block elements (Groups 1 and 2) have 1 or 2 outer shell electrons, which are easily
lost to form positive ions with the electron configuration of an inert gas. For example, Na: 1s² 2s²
2p⁶ 3s¹ → Na⁺: 1s² 2s² 2p⁶ (configuration of Neon). Group 0 elements have completely filled
subshells making them inert .
Question 2
Atomic radius decreases across a period. What is the correct explanation for this trend?
A) Number of protons decreases, reducing nuclear attraction
B) Number of protons increases, pulling electrons closer to the nucleus, and extra electrons are
added to the outer energy level so they don't provide extra shielding
C) Shielding increases significantly, offsetting nuclear charge
D) Electron repulsion causes orbitals to expand
Correct answer: B
Rationale: Across a period, as the number of protons increases, the positive charge on the
nucleus increases, causing electrons to be pulled closer to the nucleus. The extra electrons
gained across a period are added to the outer energy level, so they don't provide any extra
shielding. This causes atomic radius to decrease .
,Question 3
Ionisation energy increases across a period. Which of the following is a contributing factor?
A) The nuclear charge decreases, reducing attraction
B) The number of protons increases, providing stronger nuclear attraction, with little extra
shielding or distance to lessen this attraction
C) Shielding increases dramatically, making electrons easier to remove
D) The atomic radius increases, reducing nuclear attraction
Correct answer: B
Rationale: Across a period, the number of protons increases, providing stronger nuclear
attraction. All extra electrons are at roughly the same energy level, even if they are in different
orbital types. There is generally little extra shielding or extra distance to lessen nuclear
attraction, so ionisation energy increases .
Question 4
There is a drop in ionisation energy between Groups 2 and 3. What explains this anomaly?
A) Group 3 elements have their outermost electron in a p orbital rather than an s orbital
B) Group 2 elements have full subshells, making them more stable
C) Increased nuclear charge in Group 3 makes electron removal easier
D) The outermost electron in Group 3 is closer to the nucleus
Correct answer: A
Rationale: The drop in ionisation energy between Groups 2 and 3 occurs because group 3
elements have their outermost electron in a p orbital rather than an s orbital. The outermost
electron is further away from the nucleus, and the shielding provided by the s orbital below the p
orbital overrides the effect of increased nuclear attraction .
Question 5
There is a drop in ionisation energy between Groups 5 and 6. What causes this?
,A) Increased nuclear charge in Group 6
B) Electron repulsion in Group 6 elements between two electrons in a p orbital
C) Full subshell stability in Group 5 elements
D) Both B and C
Correct answer: D
Rationale: Elements with singly filled or full subshells are more stable than those with partially
filled shells, hence they have higher first ionisation energies. The drop between Groups 5 and 6
is due to electron repulsion; the repulsion between two electrons in a p orbital in Group 6
elements means they are easier to remove than a singly occupied p orbital in Group 5 elements
.
Question 6
What two subatomic particles have the most mass but occupy very little of the volume of an
atom?
A) Electrons and protons
B) Protons and neutrons
C) Electrons and neutrons
D) Positrons and electrons
Correct answer: B
Rationale: Protons and neutrons are located in the nucleus, which occupies very little of the
atom's volume but contains nearly all of its mass. Electrons have much less mass and occupy
the majority of the atom's volume .
Question 7
Isotopes are defined as:
A) Atoms of different elements with the same number of neutrons
B) Atoms of the same element with the same number of protons but different numbers of
neutrons
C) Different atomic forms with the same number of electrons
D) Atoms with the same mass number but different atomic numbers
Correct answer: B
, Rationale: Isotopes are different atomic forms of the same element. They have the same
number of protons (same atomic number) but a different number of neutrons .
Question 8
Relative atomic mass is defined as:
A) The mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12
B) The weighted mean mass of an atom of an element compared to 1/12th the mass of an atom
of carbon-12
C) The total number of protons and neutrons in an atom
D) The mass of one mole of an element in grams
Correct answer: B
Rationale: Relative atomic mass is the weighted mean mass of an atom of an element,
compared to 1/12th the mass of an atom of carbon-12. It accounts for the natural abundance of
different isotopes .
Question 9
The s, p, d, and f subshells are designated by:
A) Their relative energy levels only
B) The number of electrons they can hold
C) The shape of the orbitals within the subshell
D) Their position in the periodic table
Correct answer: C
Rationale: s, p, d, and f subshells are designated by the shape of the orbitals within them. s
orbitals are spherical, p orbitals are dumbbell-shaped, and d/f orbitals have more complex
shapes .
Question 10
How many electrons can occupy a single p orbital?
PRACTICE EXAM
SECTION 1: ATOMIC STRUCTURE & PERIODICITY
Questions 1–25
Question 1
Electronic configuration decides the chemical properties of an element (periodicity). Which
statement correctly describes s-block elements?
A) They have completely filled d subshells and are unreactive
B) They have 1 or 2 outer shell electrons, which are easily lost to form positive ions
C) They gain electrons to form negative ions with inert gas configuration
D) They share electrons to form covalent bonds exclusively
Correct answer: B
Rationale: s-block elements (Groups 1 and 2) have 1 or 2 outer shell electrons, which are easily
lost to form positive ions with the electron configuration of an inert gas. For example, Na: 1s² 2s²
2p⁶ 3s¹ → Na⁺: 1s² 2s² 2p⁶ (configuration of Neon). Group 0 elements have completely filled
subshells making them inert .
Question 2
Atomic radius decreases across a period. What is the correct explanation for this trend?
A) Number of protons decreases, reducing nuclear attraction
B) Number of protons increases, pulling electrons closer to the nucleus, and extra electrons are
added to the outer energy level so they don't provide extra shielding
C) Shielding increases significantly, offsetting nuclear charge
D) Electron repulsion causes orbitals to expand
Correct answer: B
Rationale: Across a period, as the number of protons increases, the positive charge on the
nucleus increases, causing electrons to be pulled closer to the nucleus. The extra electrons
gained across a period are added to the outer energy level, so they don't provide any extra
shielding. This causes atomic radius to decrease .
,Question 3
Ionisation energy increases across a period. Which of the following is a contributing factor?
A) The nuclear charge decreases, reducing attraction
B) The number of protons increases, providing stronger nuclear attraction, with little extra
shielding or distance to lessen this attraction
C) Shielding increases dramatically, making electrons easier to remove
D) The atomic radius increases, reducing nuclear attraction
Correct answer: B
Rationale: Across a period, the number of protons increases, providing stronger nuclear
attraction. All extra electrons are at roughly the same energy level, even if they are in different
orbital types. There is generally little extra shielding or extra distance to lessen nuclear
attraction, so ionisation energy increases .
Question 4
There is a drop in ionisation energy between Groups 2 and 3. What explains this anomaly?
A) Group 3 elements have their outermost electron in a p orbital rather than an s orbital
B) Group 2 elements have full subshells, making them more stable
C) Increased nuclear charge in Group 3 makes electron removal easier
D) The outermost electron in Group 3 is closer to the nucleus
Correct answer: A
Rationale: The drop in ionisation energy between Groups 2 and 3 occurs because group 3
elements have their outermost electron in a p orbital rather than an s orbital. The outermost
electron is further away from the nucleus, and the shielding provided by the s orbital below the p
orbital overrides the effect of increased nuclear attraction .
Question 5
There is a drop in ionisation energy between Groups 5 and 6. What causes this?
,A) Increased nuclear charge in Group 6
B) Electron repulsion in Group 6 elements between two electrons in a p orbital
C) Full subshell stability in Group 5 elements
D) Both B and C
Correct answer: D
Rationale: Elements with singly filled or full subshells are more stable than those with partially
filled shells, hence they have higher first ionisation energies. The drop between Groups 5 and 6
is due to electron repulsion; the repulsion between two electrons in a p orbital in Group 6
elements means they are easier to remove than a singly occupied p orbital in Group 5 elements
.
Question 6
What two subatomic particles have the most mass but occupy very little of the volume of an
atom?
A) Electrons and protons
B) Protons and neutrons
C) Electrons and neutrons
D) Positrons and electrons
Correct answer: B
Rationale: Protons and neutrons are located in the nucleus, which occupies very little of the
atom's volume but contains nearly all of its mass. Electrons have much less mass and occupy
the majority of the atom's volume .
Question 7
Isotopes are defined as:
A) Atoms of different elements with the same number of neutrons
B) Atoms of the same element with the same number of protons but different numbers of
neutrons
C) Different atomic forms with the same number of electrons
D) Atoms with the same mass number but different atomic numbers
Correct answer: B
, Rationale: Isotopes are different atomic forms of the same element. They have the same
number of protons (same atomic number) but a different number of neutrons .
Question 8
Relative atomic mass is defined as:
A) The mass of an atom of an element compared to 1/12th of the mass of an atom of carbon-12
B) The weighted mean mass of an atom of an element compared to 1/12th the mass of an atom
of carbon-12
C) The total number of protons and neutrons in an atom
D) The mass of one mole of an element in grams
Correct answer: B
Rationale: Relative atomic mass is the weighted mean mass of an atom of an element,
compared to 1/12th the mass of an atom of carbon-12. It accounts for the natural abundance of
different isotopes .
Question 9
The s, p, d, and f subshells are designated by:
A) Their relative energy levels only
B) The number of electrons they can hold
C) The shape of the orbitals within the subshell
D) Their position in the periodic table
Correct answer: C
Rationale: s, p, d, and f subshells are designated by the shape of the orbitals within them. s
orbitals are spherical, p orbitals are dumbbell-shaped, and d/f orbitals have more complex
shapes .
Question 10
How many electrons can occupy a single p orbital?
