Do nonmetals tend to form positive or negative ions?
Non-metals TEND to form negative ions..........
Non-metals tend to form anions........Because the non-metal comes from the right hand side of the Periodic Table as we face it, its nuclear charge is very poorly shielded by its INCOMPLETE valence electronic shell, and this results in the well-known contraction of atomic radii across the Table from left to right. Halogen and chalcogen atoms thus typically form
On the other hand, once a valence shell is completed, the full valence shell shields the nuclear charge fairly effectively, so that the next electron is added to the a more distant electornic shell. The result? (i) Atomic radii decrease across the Period from left to right, AND (ii) metals tend to form CATIONS, and (iii), in answer to your specific question, non metals tend to form anions: i.e. oxides; sulfides; phosphides; nitrides; halides. This effect could also be demonstrated by the increase in ionization energies observed going across a Period from left to right,