Nonmetals tend to gain electrons to form ions because they have a higher electronegativity compared to metals. This means they have a stronger attraction for electrons. When nonmetals gain electrons, they achieve a stable electron configuration, similar to that of noble gases.
For example, consider chlorine (Cl), a nonmetal. Chlorine has 7 electrons in its outermost shell. By gaining one electron, it achieves a full outer shell with 8 electrons, becoming a chloride ion (Cl⁻). This ion has a negative charge because it has one more electron than protons.
Therefore, the correct answer is:
d) gain negative
Nonmetals gain electrons to form negatively charged ions, known as anions.