( ( ( ( 599 half-life ) ( The time ) ) ( it ( ( takes ( for ( ( half ( the isotopes ) ) ( in ( ( a sample ) ( of ( ( an element ) ( to decay ) ) ) ) ) ) ) ) ( into ( a ( second isotope ) ) ) ) ) ) . )
(ROOT (NP (NP (NP (CD 599) (NN half-life)) (NP (DT The) (NN time))) (SBAR (S (NP (PRP it)) (VP (VBZ takes) (PP (IN for) (NP (NP (PDT half) (DT the) (NNS isotopes)) (PP (IN in) (NP (NP (DT a) (NN sample)) (PP (IN of) (NP (NP (DT an) (NN element)) (PP (TO to) (NP (NN decay))))))))) (PP (IN into) (NP (DT a) (JJ second) (NN isotope)))))) (. .)))
599 half-life The time it takes for half the isotopes in a sample of an element to decay into a second isotope.
(ROOT (S (NP (DT The) (NN term) (NN half-life)) (VP (VBZ decribes) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NP (NN time)) (VP (VBN required) (PP (IN for) (NP (NP (NN half)) (PP (IN of) (NP (DT the) (JJ original) (NN material))))) (PP (TO to) (NP (NP (NN decay)) (PP (IN in) (NP (DT an) (NN isotope)))))))))) (. .)))