Final answer:
The elements in Group 18, also known as the noble gases, are the least likely to form bonds because they already possess a full valence shell, making them chemically inert.
Step-by-step explanation:
The elements least likely to form bonds are found in Group 18. This group is known as the noble gases, which includes elements like helium, neon, and argon. Noble gases have a completely filled valence shell and are thus chemically inert because they already have the maximum number of valence electrons in their outer shell, which makes them unlikely to gain or lose electrons to form bonds.
While the halogens in Group 17 are very reactive and eager to gain one electron to achieve a full valence shell, the noble gases in Group 18 have no such requirement. Similarly, the Group 1 metals easily lose one electron to form cations, and elements in Group 14 need to gain or lose four electrons for stability, both of which are starkly different from the inertness of noble gases.