There's no single element with a "full electron shell" in the way the term is usually understood. Here's why:

* Electron Shells and Stability: Elements are most stable when their outermost electron shell (valence shell) is filled.

* Different Shells, Different Numbers: Each shell has a different maximum number of electrons it can hold. For example:

* The first shell (n=1) holds up to 2 electrons.

* The second shell (n=2) holds up to 8 electrons.

* The third shell (n=3) holds up to 18 electrons.

* Noble Gases: The elements that naturally have a full valence shell are called noble gases. They are found in Group 18 of the periodic table. Examples include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).

So, to answer your question more directly:

* Helium (He) is the only element with a completely full shell (the first shell).

* All the other noble gases have a full valence shell, but not a completely full electron configuration.

Let me know if you'd like to know more about electron shells or noble gases!