432.2 years

DECAY PATHWAY: Americium-242, half-life 16.02 hrs, 17.3% decays via electron capture, 0.751 MeV, to plutonium-242, half-life 373,300 years.

It decays by emission of a α-particle to 237Np; the half-life of this decay was first determined as 510±20 years but then corrected to 432.2 years. The second isotope 242Am was produced upon neutron bombardment of the already-created 241Am.

How to calculate the half-life

1. Determine the initial amount of a substance.
2. Determine the final amount of a substance – for instance, N(t) = 2.1 kg .
3. Measure how long it took for that amount of material to decay.
4. Input these values into our half-life calculator.

The half-life of a radioactive substance is a characteristic constant. It measures the time it takes for a given amount of the substance to become reduced by half as a consequence of decay, and therefore, the emission of radiation. When it decays to stable nickel, it emits two relatively high-energy gamma rays.

The half-life of an isotope is used to describe the rate at which the isotope will decay and give off radiation. Using the half-life, it is possible to predict the amount of radioactive material that will remain after a given amount of time.

Drugs or substances that have a shorter half-life tend to act very quickly, but their effects wear off rapidly, meaning that they usually need to be taken several times a day to have the same effect.

Radioisotopes with short half-lives are dangerous for the straightforward reason that they can dose you very heavily (and fatally) in a short time. Such isotopes have been the main causes of radiation poisoning and death after above-ground explosions of nuclear weapons.

The half-life of a drug is the time it takes for the amount of a drug’s active substance in your body to reduce by half.

Fluoxetine, which has the longest half-life of the SSRIs (see Table 1), appears to produce the fewest withdrawal symptoms, while paroxetine, which has the shortest half-life, produces the most pronounced discontinuation effects.

The half-life equal to the dosing interval at steady-state where the maximum concentration at steady-state is twice the maximum concentration found for the first dose and where the fall off to the trough concentration from the maximum concentration is consistent with this half-life.

Isotopes with a long half-life decay very slowly, and so produce fewer radioactive decays per second; their intensity is less. Istopes with shorter half-lives are more intense. In nuclear waste, isotopes with very short half-lives, say a few days or even a few weeks, are not the major concern.

A half-life is the time taken for something to halve its quantity. The term is most often used in the context of radioactive decay, which occurs when unstable atomic particles lose energy. Twenty-nine elements are known to be capable of undergoing this process.

The half-life of a radioactive material can be changed using time dilation effects. According to relativity, time itself can be slowed down. Everything that experiences time can therefore be given a longer effective lifetime if time is dilated. This can be done in two ways.

50 percent

5,730 years

approximately 5730 years

The half-life of carbon-14 is the amount of time it takes for one-half of the original amount to disappear by radioactive decay. After 50,000 years, a fossil won’t have any radiocarbon left in it. Carbon-14 will have all disappeared by radioactive decay.

Carbon-14 has a half life of 5730 years. This means it takes 5730 years for half of the carbon-14 atoms to decay to carbon-12 in a given sample (eg: 100 carbon-14, one half life = 50 carbon-14, 50 carbon-12).