how and when hallide ions areformed also illustrate with an example?
Dear student!
Halide ion is a halogen atom bearing a negative charge as: X-1 like F-, Cl- , Br- etc
These, ions are formed when the halogens come in contact with an electropositive or a comparatively less electronegative element which could donate an electron to the X atom so that it first forms a halide ion which further combines as:
Na -> Na+ + e-
Cl + e- -> Cl- (chloride ion)
Now, Na+ + Cl- -> NaCl