GCSE · Chemistry · AQA · Spec 8462

Electronic structure

How electronic structure is built

Follow the arrangement from the lowest available energy level outwards.

  1. Start at the lowest levelElectrons occupy the lowest available energy levels first, so begin with the innermost available shell.
  2. Move outwards when neededElectrons occupy higher energy levels only after the lower available levels have been used.
  3. Record the arrangementThe finished electronic structure can be represented as numbers or shown as a diagram.

Unpacking sodium: 2,8,1

Each number tells you how many electrons are in one energy level.

Two ways to show electronic structure

Number representationvsDiagram representation

Both forms represent the same arrangement of electrons.

Focus

What you see

Number representation

Numbers show how many electrons occupy each energy level.

Diagram representation

A diagram shows the electrons arranged across the energy levels.

The insight

The two forms look different but represent the same electronic structure.

Sodium example

Number representation

Sodium is written as 2,8,1.

Diagram representation

A diagram represents two electrons in the lowest level, eight in the second and one in the third.

What you must be able to do

Number representation

Represent the first twenty elements using numbers.

Diagram representation

Represent the first twenty elements using diagrams.

Electronic structure vocabulary

Keep the language tied to what the representation is showing.

Predict, then check

Use the order of the numbers rather than guessing from their size.

In the electronic structure 2,8,1, which statement correctly describes the electrons?

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Learn how electrons occupy energy levels and how to show their arrangement in two different forms.

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