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.
Similarly, What is considered a long half-life?
Drugs that have a long half-life include
The high may last only a few hours; however, residual effects can linger for up to 24 hours.
Additionally, What is a half-life simple definition? half-life, in radioactivity, the interval of time required for one-half of the atomic nuclei of a radioactive sample to decay (change spontaneously into other nuclear species by emitting particles and energy), or, equivalently, the time interval required for the number of disintegrations per second of a radioactive …
What does a long half-life mean radioactive decay?
Half-life (symbol t1⁄2) is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive.
What atom has the shortest half-life?
Uranium-234 has the shortest half-life of them all at 245,500 years, but it occurs only indirectly from the decay of U-238. In comparison, the most radioactive element is polonium. It has a half-life of a mere 138 days. Still, uranium has explosive potential, thanks to its ability to sustain a nuclear chain reaction.
What drug has the shortest half-life?
This class of drugs has evolved from a drug such as amlodipine, with a long duration of action related to prolonged plasma half-life, to lercanidipine, which has the shortest plasma half-life relative to its intrinsically long duration of action.
What is the best definition of half-life?
or half life, half·life
the time required for one half the atoms of a given amount of a radioactive substance to disintegrate. … the time required for the activity of a substance taken into the body to lose one half its initial effectiveness. Informal. a brief period during which something flourishes before dying out.
What is a half-life in earth science?
Half-life is a term that describes time. The definition is: The time required for one-half of the radioactive (parent) isotopes in a sample to decay to radiogenic (daughter) isotopes. In other words, it is the lifetime of half the radioactive isotopes in a system.
What is a half-life quizlet?
Half life definition. the average time it takes for the number of nuclei in a radioactive isotope sample to halve. the radioactivity of a sample always. decreases over time.
How does half-life relate to radioactive decay?
The decay of radioactive elements occurs at a fixed rate. The half-life of a radioisotope is the time required for one half of the amount of unstable material to degrade into a more stable material. … After ten half-lives, less than one-thousandth of the original activity will remain.
Why is a short half-life beneficial?
Some radioisotopes used in nuclear medicine have short half-lives, which means they decay quickly and are suitable for diagnostic purposes; others with longer half-lives take more time to decay, which makes them suitable for therapeutic purposes.
How does half-life affect radioactivity?
The longer the half-life of a nucleus, the lower the radioactive activity. A nucleus with a half-life that is a million times greater than another will be a million times less radioactive. A ‘half-life’ is defined as the amount of time taken for the number of nuclei present in a sample at a given time to exactly halve.
What is the fastest half-life?
The scientists registered 128 alpha-particle events over 5 days and found an unexpected line in the spectrum at 3.14 MeV – now attributed to bismuth-209 decay. The half-life was calculated to be (1.9 +/- 0.2 ) x 1019 years, which is in good agreement with the theoretical prediction of 4.6 x 1019 years.
Which element has a half-life of only a few minutes?
Californium is a radioactive element, one of the actinide series. There are twenty radioisotopes of californium, with mass numbers from 237 to 256. The most stable is californium-251, with a half-life of 898 years, but the first to be discovered was californium-245, which has a half-life of only 44 minutes.
Does a shorter half-life mean more radioactive?
In general there is an inverse relation between the half-life and the intensity of radioactivity of an isotope. 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.
What is the half-life of Tylenol?
The half-life of acetaminophen is approximately 2 to 3 hours after therapeutic doses, yet can be increased to more than 4 hours in patients with hepatic injury.
What are the two definitions of half-life?
Half-life is the time it takes for half of the unstable nuclei in a sample to decay or for the activity of the sample to halve or for the count rate to halve. Count-rate is the number of decays recorded each second by a detector, such as the Geiger-Muller tube. … The half-life of radioactive carbon-14 is 5,730 years.
What is the scientific definition of half-life quizlet?
What is the scientific definition of half-life? the amount of time over which the number of parent isotopes decreases by half. Two containers hold the same radioactive isotope.
What is half-life of a reaction?
The half-life of a reaction is the time required for a reactant to reach one-half its initial concentration or pressure. For a first-order reaction, the half-life is independent of concentration and constant over time.
Why is it called half-life?
The name Half-Life was chosen because it was evocative of the theme, not clichéd, and had a corresponding visual symbol: the Greek letter λ (lower-case lambda), which represents the decay constant in the half-life equation.
What is a 1/2 life?
Half-life (t1/2) is defined as the amount of time required for the drug concentration measured in plasma (or other biological matrices) to be reduced to exactly half of its starting concentration or amount. After IV dosing, the drug concentrations in plasma decline due to both elimination and distribution [15].
What is a half-life chemistry quizlet?
Half-life. The length of time required of half of a given sample of a radioisotope to decay. Radioisotope. Isotope that is radioactive or emits radiation.
What is the definition of a half-life quizlet geology?
What is the scientific definition of half-life? the amount of time over which the number of parent isotopes decreases by half. Two containers hold the same radioactive isotope.