half-life (redirected from Chemical half-life)

half-life (hflf, häf-)

n.

1. Physics The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay.

2. Biology

a. The time required for half the quantity of a drug or other substance deposited in a living organism to be metabolized or eliminated by normal biological processes. Also called biological half-life.

b. The time required for the radioactivity of material taken in by a living organism to be reduced to half its initial value by a combination of biological elimination processes and radioactive decay.

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half-life

n

1. (Physics / General Physics) the time taken for half of the atoms in a radioactive material to undergo decay. Symbol τ

2. (Life Sciences & Allied Applications / Biology) the time required for half of a quantity of radioactive material absorbed by a living tissue or organism to be naturally eliminated (biological half-life) or removed by both elimination and decay (effective half-life)

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half-life  (hflf)

The average time needed for half the nuclei in a sample of a radioactive substance to undergo radioactive decay. The half-life of a substance does not equal half of its full duration of radioactivity. For example, if one starts with 100 grams of radium 229, whose half-life is 4 minutes, then after 4 minutes only 50 grams of radium will be left in the sample, after 8 minutes 25 grams will be left, after 12 minutes 12.5 grams will be left, and so on.

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The time required for the activity of a given radioactive species to decrease to half of its initial value due to radioactive decay. The half-life is a characteristic property of each radioactive species and is independent of its amount or condition. The effective half-life of a given isotope is the time in which the quantity in the body will decrease to half as a result of both radioactive decay and biological elimination.

Thesaurus

Noun

1.

half-life - the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate) half life period, period of time, time period - an amount of time; "a time period of 30 years"; "hastened the period of time of his recovery"; "Picasso's blue period"

Translations

half-life [ˈhɑːflaɪf] N (half-lives (pl)) (Phys) → media vida f

half-life [ˌhɑːfˈlaɪf] n (Phys) → tempo di dimezzamento