Boost your 14–16 students’ confidence drawing electron configuration diagrams with these easy to follow steps

An electron configuration diagram is a model that depicts the position of electrons as they orbit the nucleus of an atom. Electrons are represented by dots or crosses and are positioned in energy levels, or ‘shells’, around the central nucleus. This is sometimes called the Bohr, or the ‘solar system’, model.

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This infographic is designed to be displayed as a poster in the classroom, although it can also be displayed on a projector or printed as a handout.

Use the accompanying fact sheet and worksheet to get your students drawing electron configuration diagrams.

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EiC - Electron Shells -Bohr copy
Source: © Dan Bright
EiC - Electron Shells - Bohr
Source: © Dan Bright

Neils Bohr was the first to suggest the idea that electrons orbit the atom in fixed shells, or energy levels, in 1913. Bohr observed that bursts of energy emitted from hydrogen atoms, visible as light, only occurred at specific wavelengths. He suggested this was due to electrons moving between energy levels rather than being scattered randomly around the nucleus. He was awarded a Nobel prize for his work.

Bohr impressed fellow scientist Rutherford, who discovered the nucleus of the atom, but didn’t win over JJ Thomson whose ‘plum pudding’ model of the atom was replaced by Rutherford’s, then Bohr’s, model

In the Bohr model, there are a few rules that will help you draw accurate diagrams.

  • Electrons must occupy the lowest available shell, closest to the nucleus.
  • The maximum number of electrons that can fill each shell is:
    • two in the first shell,
    • eight in the second shell,
    • eight in the third shell.
  • Calcium, the 20th element, has two further electrons that go in the fourth shell.

In the shorthand notation for electron configuration, the number of electrons in each shell can be written rather than drawn. Each shell is separated by a full stop or a comma. For nitrogen this would be 2.5 or 2,5 and for calcium this would be 2.8.8.2 or 2,8,8,2.

Did you know …?

The arrangement of an element’s electrons tells you where it is on the periodic table. The number of shells shows which period, or row, it’s in and the number of electrons in the outer shell shows which group it’s in.

How to draw an electron configuration diagram

2-electron diagram-01
Source: © Dan Bright
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Source: © Dan Bright
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Source: © Dan Bright

Find the element on the periodic table. The atomic number tells you how many electrons to draw in total. For example, potassium has 19 electrons

Draw a small circle and write the symbol in the centre. This represents the nucleus

Draw a circle around the nucleus. This is the first electron shell

Add up to two electrons to the first electron shell. Electrons are usually represented by a dot or cross

Draw another circle around the first shell. This is the second shell

Add up to eight electrons to the second shell

Draw another circle around the second electron shell. This is the third shell

Add up to eight electrons to the third shell

Draw the last circle around the third shell. This is the fourth electron shell

Add up to two electrons to the fourth electron shell. For potassium, only one electron is added to this shell

Now draw the first 20 elements

3-nitrogen-01
Source: © Dan Bright
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Source: © Dan Bright

Use the steps above to draw electron configuration diagrams of the first 20 elements

The position of electrons may depend on what you need to draw next

Want other step-by-step guides to drawing bonds? Check out these articles with resources on drawing dot and cross diagrams for:

All illustrations © Dan Bright

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Kirsty Patterson is the assistant editor for teaching resources at the Royal Society of Chemistry.View full profile

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