To write condensed electron configurations (also called abbreviated electron configurations) for elements we first write the full electron configuration for the element. Once we have the full configuration we put brackets around the config for the Noble Gas core. We can then replace this with the element symbol for the Noble Gas, leaving the rest of the configuration visible (these are the valence electrons).
For example, for Calcium, atomic number 20 on the Periodic Table:
Calcium 1s2 2s2 2p6 3s2 3p6 4s2 (full)
Calcium [1s2 2s2 2p6 3s2 3p6] 4s2 (Noble Gas in brackets)
Calcium [Ar] 4s2 (Condensed config)
For help writing electron configurations for elements:
• Introduction to Writing Electron Configurations: • Introduction to Electr...
• Writing Electron Configs Using only the Periodic Table: • Writing Electron Confi...
• Electron Configurations Chart: • Using the Electron Con...
• Exceptions for Electron Configurations: • Electron Configuration...
The condensed electron configuration notation provides an easy way for scientists to write and communicate how electrons are arranged around the nucleus of an atom. It places an emphasis on the valence electrons (the electrons written after the Noble Gas core). This makes it easier to understand and predict how atoms will interact to form chemical bonds.