Atomic structure - (CCEA)Writing and drawing electronic configuration

Scientists’ ideas about atoms have changed over time. Today, they agree that atoms have a positively-charged nucleus made of protons and neutrons, and negatively-charged electrons that orbit the nucleus in shells.

Part ofCombined ScienceAtomic structure and the periodic table

Writing and drawing electronic configuration

Take sodium as an example. Sodium has 11 . It has:

  • 2 electrons in the first shell
  • 8 electrons in the second shell
  • 1 electron in the third shell

You can write sodium’s with numbers and commas: 2,8,1

The electronic configuration of sodium can be shown in a diagram. The dots represent electrons. Electrons may be shown using dots or crosses.

Structure of a sodium atom
Figure caption,
A diagram of the electronic configuration of an atom of sodium.

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