( ( ( The amount ) ( of ( energy ( that ( you ( ( ( need ( to ( ( dump ( into ( a ( chemical reaction ) ) ) ) ( ( in order ) ( to ( start it ) ) ) ) ) ) or ) ( activate it ) ) ) ) ) ) ) ( ( is ( called ( the ( activation energy ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN energy)) (SBAR (IN that) (S (NP (PRP you)) (VP (VP (VBP need) (S (VP (TO to) (VP (VB dump) (PP (IN into) (NP (DT a) (NN chemical) (NN reaction))) (SBAR (IN in) (NN order) (S (VP (TO to) (VP (VB start) (NP (PRP it)))))))))) (CC or) (VP (VBP activate) (NP (PRP it))))))))) (VP (VBZ is) (VP (VBN called) (NP (DT the) (NN activation) (NN energy)))) (. .)))
The amount of energy that you need to dump into a chemical reaction in order to start it or activate it is called the activation energy.
(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))))) (. .)))