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In a chemical reaction, the half-life of a species is the time it takes for the concentration of that substance to fall to half of its initial value. In a first-order reaction the half-life of the reactant is ln (2)/λ, where λ (also denoted as k) is the reaction rate constant.
The half-life of a reaction (\(t_{1/2}\)), is the amount of time needed for a reactant concentration to decrease by half compared to its initial concentration. Its application is used in chemistry and medicine to predict the concentration of a substance over time.
The half-lives of radioactive isotopes can be used to date objects. The half-life of a reaction is the time required for the reactant concentration to decrease to one-half its initial value. The half-life of a first-order reaction is a constant that is related to the rate constant for the reaction: t 1 /2 = 0.693/ k .
Half-life, in radioactivity, the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay, or, equivalently, the time interval required for the number of disintegrations per second of a radioactive material to decrease by one-half.
- The Editors of Encyclopaedia Britannica
Decay graphs and half lives article. Google Classroom. How can scientists tell when something is releasing radiation? We know that radiation is more than just the spooky, silent threat that we see in movies. Healthcare providers can actually harness the unique properties of radiation to look inside the human body and diagnose diseases in new ways.
Half-life is the time required for half of a radioactive sample to decay. Half-life cannot be changed—nuclei cannot be forced to decay faster or slower. Additionally, we cannot predict when an individual nucleus will decay.
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- Mahesh Shenoy
The half-life of a radioactive isotope is the amount of time it takes for one-half of the radioactive isotope to decay. The half-life of a specific radioactive isotope is constant; it is unaffected by conditions and is independent of the initial amount of that isotope. Consider the following example.
