( ( Because ( oxygen ( is ( the ( second-most ( electronegative element ) ) ) ) ) ) ( , ( it ( either ( ( ( ( ( ( gains ( two electrons ) ) ( to ( form ( ( ( the ( O 2 ) ) - ) ion ) ) ) ) , ) or ) ( has ( ( ( the ( lion 's ) ) share ) ( of ( electrons ( in ( a ( covalent compound ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (SBAR (IN Because) (S (NP (NN oxygen)) (VP (VBZ is) (NP (DT the) (JJ second-most) (NN electronegative) (NN element))))) (, ,) (NP (PRP it)) (ADVP (RB either)) (VP (VP (VBZ gains) (NP (CD two) (NNS electrons)) (S (VP (TO to) (VP (VB form) (NP (NP (DT the) (NNP O) (CD 2)) (: -) (NP (NN ion))))))) (, ,) (CC or) (VP (VBZ has) (NP (NP (NP (DT the) (NN lion) (POS 's)) (NN share)) (PP (IN of) (NP (NP (NNS electrons)) (PP (IN in) (NP (DT a) (JJ covalent) (NN compound)))))))) (. .)))
Because oxygen is the second-most electronegative element, it either gains two electrons to form the O 2- ion, or has the lion's share of electrons in a covalent compound.
(ROOT (S (NP (NNP Oxygen)) (VP (VBZ is) (NP (NP (DT the) (NN name)) (PP (IN of) (NP (DT the) (JJ second) (ADJP (RBS most) (JJ electronegative)) (NN element))))) (. .)))