( ( All ( chemical reactions ) ) ( ( require ( ( activation energy ) ( to ( get started ) ) ) ) . ) )
(ROOT (S (NP (DT All) (NN chemical) (NNS reactions)) (VP (VBP require) (S (NP (NN activation) (NN energy)) (VP (TO to) (VP (VB get) (VP (VBN started)))))) (. .)))
All chemical  reactions require activation energy to get started.
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN energy)) (VP (VBN required) (S (VP (TO to) (VP (VB begin) (NP (DT a) (JJ chemical) (NN reaction))))))))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (DT the) (NN activation) (NN energy))))) (. .)))