( ( Elemental potassium ) ( ( is ( ( a ( soft ( silvery-white ( alkali metal ) ) ) ) ( that ( ( ( ( oxidizes rapidly ) ( in air ) ) and ) ( ( ( ( reacts vigorously ) ( with water ) ) , ) ( ( ( ( generating ( sufficient heat ) ) ( to ( ignite ( hydrogen ( emitted ( in ( the reaction ) ) ) ) ) ) ) and ) ( burning ( with ( a ( lilac ( - ( colored flame ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Elemental) (NN potassium)) (VP (VBZ is) (NP (NP (DT a) (JJ soft) (JJ silvery-white) (NN alkali) (NN metal)) (SBAR (WHNP (WDT that)) (S (VP (VP (VBZ oxidizes) (ADVP (RB rapidly)) (PP (IN in) (NP (NN air)))) (CC and) (VP (VBZ reacts) (ADVP (RB vigorously)) (PP (IN with) (NP (NN water))) (, ,) (S (VP (VP (VBG generating) (NP (JJ sufficient) (NN heat)) (S (VP (TO to) (VP (VB ignite) (NP (NP (NN hydrogen)) (VP (VBN emitted) (PP (IN in) (NP (DT the) (NN reaction))))))))) (CC and) (VP (VBG burning) (PP (IN with) (NP (DT a) (JJ lilac) (: -) (NN colored) (NN flame)))))))))))) (. .)))
Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and reacts vigorously with water, generating sufficient heat to ignite hydrogen emitted in the reaction and burning with a lilac- colored flame .
(ROOT (S (NP (NNP Water)) (VP (VBZ is) (NP (NP (DT an) (NN oxide)) (PP (IN of) (NP (NN hydrogen))))) (. .)))