Helium 4 is a complete tetrahedron. It consists of 4 protons in a triangular shape with 2 inner electrons. The other 2 electrons are in the outer orbital (complete S-orbital).

He4 is stable and can be seen as 2 Deuterium nuclei merged together. This shape is the most fundamental repeating geometric grouping (nuclet) that the further atomic structure is based upon. See the "Nuclets - Building Blocks of the Nucleus" page.

He4 is considered the first noble element.