( ( Ionic bonds ) ( ( are ( formed ( when ( atoms ( ( become ions ) ( by ( ( ( gaining or ) losing ) electrons ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Ionic) (NNS bonds)) (VP (VBP are) (VP (VBN formed) (SBAR (WHADVP (WRB when)) (S (NP (NNS atoms)) (VP (VBP become) (NP (NNS ions)) (PP (IN by) (S (VP (VBG gaining) (CC or) (VBG losing) (NP (NNS electrons)))))))))) (. .)))
Ionic bonds are formed when atoms become ions by gaining or losing electrons.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (DT an) (NN atom)) (VP (VBZ gains) (CC or) (VBZ loses) (NP (DT an) (NN electron))))) (NP (PRP it)) (VP (VBZ becames) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN ion))) (. .)))