AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
The electronic structure of an atom can be represented by numbers or by a…
Full specification wording
Electronic structure: The electronic structure of an atom can be represented by numbers or by a diagram.
The electronic structure of an atom shows how its electrons are arranged in energy levels or shells.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 2 of 3
Study notes
From the checked teaching notes for this specification point.
The idea
The electronic structure of an atom shows how its electrons are arranged in energy levels or shells. This arrangement can be written as a series of numbers, where each number gives the number of electrons in successive energy levels starting from the innermost. For example, the numbers 2,8,1 show two electrons in the first level, eight in the second and one in the third. Alternatively, a diagram can show a central nucleus with circles or arcs representing energy levels and dots or crosses representing electrons. Both representations carry the same information, so a question may ask for either form. The number representation is compact, while the diagram makes the relative positions of the shells clear.
What earns the marks
- A number representation lists the number of electrons in each energy level in order from the innermost level outwards.
- A diagram representation shows a nucleus with energy levels drawn as circles or arcs around it.
- Electrons in a diagram are shown as dots or crosses placed on the appropriate energy level.
- The total number of electrons in either representation equals the number of protons in the atom.
Common mistakes and how to put them right
Writing the numbers in the wrong order, such as listing outer-shell electrons first.
Put it right by starting with the innermost energy level.
Drawing a diagram with the wrong number of electrons in a shell.
Put it right by counting the electrons and checking the total equals the atomic number.
Using a diagram without a nucleus or without clear energy levels.
Put it right by including a labelled nucleus and distinct shells.
Exam tips
- Check that the numbers or diagram add up to the atomic number of the element given.
- If asked for a diagram, keep the shells evenly spaced and place electrons clearly on the correct shell.
- If asked for numbers, separate them with commas and do not include spaces that could be misread.
Try the lesson
The start of the Electronic structure: The electronic structure of an atom can be represented by numbers or by a diagram. lesson, made from checked teaching notes for this specification point.
Have a go first
Which pair of methods can both be used to represent the electronic structure of an atom?
Listen
The electronic structure of an atom shows how its electrons are arranged in energy levels or shells. This arrangement can be written as a series of numbers, where each number gives the number of electrons in successive energy levels starting from the innermost. For example, the numbers 2,8,1 show two electrons in the first level, eight in the second and one in the third. Alternatively, a diagram can show a central nucleus with circles or arcs representing energy levels and dots or crosses representing electrons. Both representations carry the same information, so a question may ask for either form. The number representation is compact, while the diagram makes the relative positions of the shells clear. A strong answer earns marks for these points. A number representation lists the number of electrons in each energy level in order from the innermost level outwards. A diagram representation shows a nucleus with energy levels drawn as circles or arcs around it. Electrons in a diagram are shown as dots or crosses placed on the appropriate energy level. The total number of electrons in either representation equals the number of protons in the atom. A common slip: Writing the numbers in the wrong order, such as listing outer-shell electrons first. Instead, starting with the innermost energy level. Exam tip: Check that the numbers or diagram add up to the atomic number of the element given.
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