( similarly ( , ( ( every ( radioactive isotope ) ) ( ( ( has ( ( ( a ( characteristic half-life ) ) -- ) ( ( the length ) ( of ( time ( for ( half ( of ( the ( original ( or ( parent atoms ) ) ) ) ) ) ) ) ) ) ) ) ( to ( decay ( to ( daughter atoms ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB similarly)) (, ,) (NP (DT every) (JJ radioactive) (NN isotope)) (VP (VBZ has) (NP (NP (DT a) (JJ characteristic) (NN half-life)) (: --) (NP (NP (DT the) (NN length)) (PP (IN of) (NP (NP (NN time)) (PP (IN for) (NP (NP (NN half)) (PP (IN of) (NP (DT the) (JJ original) (CC or) (NN parent) (NNS atoms))))))))) (PP (TO to) (NP (NP (NN decay)) (PP (TO to) (NP (NN daughter) (NNS atoms)))))) (. .)))
similarly, every radioactive isotope has a characteristic half-life -- the length of time for half of the original or parent atoms to decay to daughter atoms.
(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)))))))))) (. .)))