Final answer:
Fluorine (F), chlorine (Cl), and nitrogen (N) are likely to form negative ions (-), by gaining electrons to achieve a full valence shell, while helium (He) is a noble gas and generally non-reactive.
Step-by-step explanation:
The elements likely to form negative ions (-) are typically the nonmetals, which have a higher tendency to gain electrons rather than lose them. From the options provided, fluorine (F), chlorine (Cl), and nitrogen (N) are likely to form negative ions. These elements are located on the right side of the periodic table
Fluorine (F) has seven valence electrons and is in group 17, which means it tends to gain one electron to complete its octet, forming a fluoride ion (F⁻). Chlorine (Cl), also in group 17, behaves similarly by gaining one electron to become a chloride ion (Cl⁻). On the other hand, Nitrogen (N), in group 15, requires three more electrons to achieve a stable electron configuration similar to neon (Ne), thus forming a nitride ion (N⁻⁻⁻).
However, Helium (He) is a noble gas located in group 18 of the periodic table and is typically non-reactive due to its full valence electron shell.