Question

The noble gas configuration of oxygen is

Answer 1

The elements in the last group of Periodic Table are called noble gasses. The electron configuration of oxygen is 1s22s22p4. First 2 electrons are electrons of inner shell and the same as a configuration of previews period's noble gas Helium. So, for the sake of simplicity, the configuration of elements are written using a noble gas notation, where it consist element symbol of the last noble gas prior the period where the element is located and followed by the configuration of electrons remained.

O configuration in the noble gas notation is [He]2ss2p4