( Reactivity ( ( ( The ( relative ability ) ) ( of ( a ( substance ( to ( ( undergo ( chemical change ) ) ( ( ( by ( combining ( with ( another substance ) ) ) ) or ) ( by ( breaking down ) ) ) ) ) ) ) ) ) . ) )
(ROOT (FRAG (ADVP (RB Reactivity)) (NP (NP (DT The) (JJ relative) (NN ability)) (PP (IN of) (NP (DT a) (NN substance) (S (VP (TO to) (VP (VB undergo) (NP (NN chemical) (NN change)) (PP (PP (IN by) (S (VP (VBG combining) (PP (IN with) (NP (DT another) (NN substance)))))) (CC or) (PP (IN by) (S (VP (VBG breaking) (PRT (RP down)))))))))))) (. .)))
Reactivity The relative ability of a substance to undergo chemical change by combining with another substance or by breaking down.
(ROOT (S (NP (NP (DT The) (NN ability)) (PP (IN of) (NP (NN matter) (S (VP (TO to) (VP (VB combine) (ADVP (RB chemically)) (PP (IN with) (NP (JJ other) (NNS substances))))))))) (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (NN reactivity))))) (. .)))