( ( When ( atoms ( ( ( gain or ) lose ) electrons ) ) ) ( , ( they ( ( become ( charged ( atoms ( called ions ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NNS atoms)) (VP (VB gain) (CC or) (VB lose) (NP (NNS electrons))))) (, ,) (NP (PRP they)) (VP (VBP become) (SBAR (S (VP (VBD charged) (SBAR (S (NP (NNS atoms)) (VP (VBD called) (NP (NNS ions))))))))) (. .)))
When atoms gain or lose electrons, they become charged atoms called ions .
(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))) (. .)))