( ( The ( activation energy ) ) ( ( is ( ( the ( minimum amount ) ) ( of ( energy ( required ( to ( ( place ( ( molecules or ) atoms ) ) ( in ( ( a state ) ( ( in which ) ( they ( can ( undergo ( a ( chemical transition ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN activation) (NN energy)) (VP (VBZ is) (NP (NP (DT the) (JJ minimum) (NN amount)) (PP (IN of) (NP (NP (NN energy)) (VP (VBN required) (S (VP (TO to) (VP (VB place) (NP (NNS molecules) (CC or) (NNS atoms)) (PP (IN in) (NP (NP (DT a) (NN state)) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (PRP they)) (VP (MD can) (VP (VB undergo) (NP (DT a) (JJ chemical) (NN transition)))))))))))))))) (. .)))
The activation energy is the minimum amount of energy required to place molecules or atoms in a state in which they can undergo a chemical transition.
(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))))) (. .)))