( ( ( ( ( Each ( radioactive component ) ) ( has ( ( a ( different rate ) ) ( of ( decay ( called ( its half-life ) ) ) ) ) ) ) -- ) ( ( the time ) ( it ( takes ( the ( material ( to ( lose ( half ( of ( its radioactivity ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT Each) (JJ radioactive) (NN component)) (VP (VBZ has) (NP (NP (DT a) (JJ different) (NN rate)) (PP (IN of) (NP (NP (NN decay)) (VP (VBN called) (NP (PRP$ its) (NN half-life)))))))) (: --) (S (NP (DT the) (NN time)) (NP (PRP it)) (VP (VBZ takes) (NP (DT the) (NN material) (S (VP (TO to) (VP (VB lose) (NP (NP (NN half)) (PP (IN of) (NP (PRP$ its) (NN radioactivity)))))))))) (. .)))
Each radioactive component has a different rate of decay called its half-life -- the time it takes the material to lose half of its radioactivity.
(ROOT (S (NP (DT The) (NN decay) (NN rate)) (VP (VBZ is) (VP (VBN measured) (PP (IN in) (NP (NP (DT a) (NN unit)) (VP (VBN called) (NP (DT the) (NN half-life))))))) (. .)))