Final answer:
Main-group nonmetals, especially those in Groups 5A, 6A, and 7A, seek to gain valence electrons to achieve a noble gas electron configuration, adhering to the octet rule for stability.
Step-by-step explanation:
The types of elements that seek to gain valence electrons are primarily the main-group nonmetals, especially those in Groups 5A, 6A, and 7A of the periodic table. These elements aim to achieve a filled valence shell, commonly achieving the electron configuration of a noble gas. For instance, Group 5A elements can accept three electrons to form 3- ions, Group 6A like oxygen can accept two to form 2- ions, and Group 7A, the halogens, accept one electron to form 1- ions. The desire to fill the valence shell and achieve stability is termed the octet rule, which is a strong driver in the formation of chemical bonds.