An<unk> , also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n.<unk> s are made up of one or more<unk>  subshells, or sublevels, which have two or more orbitals with the same angular momentum quantum number l.<unk> s make up the<unk>  configuration of an atom. It can be shown that the number of<unk> s that can reside in a<unk>  is equal to 
2
n
2
{\displaystyle 2n^{2}}
 .
Electron shell
Capsid
Viral envelope
Striae
Viral tegument
Flagellum
Ribozyme
Macrocycle