Final answer:
The electron configuration with 18 electrons fully occupying the outermost energy level is known as a noble gas configuration, exemplified by the inert and chemically stable noble gases, and is tied to the octet rule of chemical stability.
Step-by-step explanation:
The electron configuration that has 18 electrons in the outer energy level with all of the orbitals filled is known as a noble gas configuration. In atoms, electrons occupy orbitals in a way described by three key pieces of information: the number of the principal quantum shell (n), the letter that designates the orbital type (subshell), and a superscript number that indicates the number of electrons in that subshell. Noble gases, such as helium, neon, and argon, possess this type of electron configuration, where all orbitals in their outermost energy level (valence shell) are filled, resulting in a stable configuration. According to the octet rule, atoms strive to complete their outer shells with eight electrons to achieve this stable arrangement, leading to low reactivity and chemical inertness as observed in noble gases.