Electronic structure - AQA GCSE Chemistry Exam Questions

Practise 18 exam-style questions on Electronic structure for AQA GCSE Chemistry. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.

18 questions
1–6 marks each
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18 questions, marked as you go

Sample questions with model answers

Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.

Question 1

2 marks

State the maximum number of electrons that can occupy the first energy level (shell) and the maximum number that can occupy the second energy level (shell).

Model answer

The first energy level can hold up to 2 electrons and the second energy level can hold up to 8 electrons.

Explanation

These limits decide how electrons are arranged: the innermost shell fills with 2 electrons before any go into the second shell, which then fills with up to 8.

Mark scheme

1 mark
first energy level: 2
1 mark
second energy level: 8

Question 2

2 marks

Lithium has atomic number 3 and sodium has atomic number 11.

Compare the electronic structures of lithium and sodium atoms.

Model answer

Lithium is 2,1 and sodium is 2,8,1. Both have one electron in their outer shell, but sodium has one more occupied shell than lithium (three shells instead of two).

Explanation

A comparison needs a similarity or difference, not just two separate structures. Having the same number of outer electrons is why lithium and sodium have similar chemical properties.

Mark scheme

1 mark
both have 1 electron in the outer shell
giving both structures (2,1 and 2,8,1) without any comparison scores 1 mark only
1 mark
sodium has one more occupied shell than lithium (3 shells compared with 2)
allow sodium has 8 more electrons / a full second shell

Question 3

3 marks

The diagram shows the electronic structures of atoms of two elements, A and B.

Atomic numbers: N = 7, O = 8, F = 9, P = 15, S = 16, Cl = 17

Identify elements A and B. Give one similarity and one difference between the electronic structures of A and B.

Electron shell diagram: particle with A in the centre and electrons 2,6 drawn on 2 shells; particle with B in the centre and electrons 2,8,6 drawn on 3 shells.

Model answer

A has 2 + 6 = 8 electrons, so it is oxygen. B has 2 + 8 + 6 = 16 electrons, so it is sulfur. Both atoms have 6 electrons in their outer shell, but B has three occupied shells while A has only two.

Explanation

Count the electrons to find the atomic number of each atom. Atoms with the same number of outer electrons are in the same group, and an extra shell means the element is one period further down.

Mark scheme

1 mark
A is oxygen and B is sulfur
both needed
1 mark
similarity: both have 6 electrons in the outer shell
1 mark
difference: B has three occupied shells and A has two
allow B has 8 more electrons / B has 16 electrons and A has 8

Question 4

4 marks

There are 2 elements in the first period (row) of the periodic table and 8 elements in the second period.

Explain this in terms of electronic structure.

Model answer

Elements in the first period have electrons only in the first shell, which can hold a maximum of 2 electrons. Hydrogen has 1 and helium has 2, so there are only 2 elements in period 1. In the second period, electrons are added one at a time to the second shell, which can hold a maximum of 8 electrons: from lithium (2,1) to neon (2,8). So there are 8 elements in period 2.

Explanation

Each element has one more electron than the one before it. A period ends when the shell being filled is full, so the number of elements in a period matches the number of electrons that shell can hold.

Mark scheme

1 mark
the first shell can hold a maximum of 2 electrons
1 mark
so only 2 elements (hydrogen and helium) have electrons in the first shell only
allow each element in period 1 adds one electron to the first shell until it is full
1 mark
the second shell can hold a maximum of 8 electrons
1 mark
so there are 8 elements (lithium to neon) as electrons are added one at a time to the second shell

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