( ( Hydrogen ( Bonds ( Hydrogen bonds ) ) ) ( ( can ( form ( whenever ( ( ( a ( ( strongly electronegative ) atom ) ) ( -LRB- ( ( ( ( ( e.g. , ) oxygen ) , ) nitrogen ) -RRB- ) ) ) ( approaches ( ( a ( hydrogen atom ) ) ( which ( ( is covalently ) ( attached ( to ( a ( second ( strongly-electronegative atom ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Hydrogen) (NNPS Bonds) (NNP Hydrogen) (NNS bonds)) (VP (MD can) (VP (VB form) (SBAR (WHADVP (WRB whenever)) (S (NP (NP (DT a) (ADJP (RB strongly) (JJ electronegative)) (NN atom)) (PRN (-LRB- -LRB-) (NP (NNP e.g.)) (, ,) (NP (NN oxygen)) (, ,) (NP (NN nitrogen)) (-RRB- -RRB-))) (VP (VBZ approaches) (NP (NP (DT a) (NN hydrogen) (NN atom)) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADVP (RB covalently)) (VP (VBN attached) (PP (TO to) (NP (DT a) (JJ second) (JJ strongly-electronegative) (NN atom))))))))))))) (. .)))
Hydrogen Bonds Hydrogen bonds can form whenever a strongly electronegative atom (e.g., oxygen, nitrogen) approaches a hydrogen atom which is covalently attached to a second strongly-electronegative atom.
(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))))) (. .)))