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Half-life in (radio)chemistry is the length of time it takes, on average, for a radionuclide (radioactive nuclide) to decay to something else, and leave one-half of its original mass behind. Half-life is logarithmic, so, after a second half-life, one quarter of the mass remains, etc., making a sequence 1/2, 1/4, 1/8, 1/16, etc.
One equation for half-life - there are several - all the same - is ...
AT = A0 2(-T/H)
... where A0 is the starting activity (or mass), AT is the activity after some time T, and H is the half-life in units of T.
One complication is that many radionuclides decay to other radionuclildes, each with their own half-life. As a result, analysis of half-life requires differentiation between different radionuclides, otherwise the results can be in error.
The reason for the last statement is that activity is defined as the number of disintegration's per unit of time, i.e. one curie of activity is defined as the amount of material that exhibits 3.7 x 1010 disintegration's (or decays) per second, and if you simply count disintegration rate, without regard to energy or other criteria, your results will often be in error.
Wiki User
∙ 12y ago
Wiki User
∙ 12y agoThe equation for half-life is ...
AT = A0 2(-T/H)
... where AT is activity at some time T, A0 is starting activity, and H is half-life in units of T.
If you wanted to solve for H, it is straightforward algebra ...
AT = A0 2(-T/H)
AT / A0 = 2(-T/H)
log2 (AT / A0) = -T/H
H = -T / log2 (AT / A0)
... Remember that log2 (x) = ln (x) / ln (2)
Wiki User
∙ 14y agoAn awful lot of statistical manipulation would be involved in arriving at an answer, but you take a known number of atoms of the element and count how many decays occur over a set time period. Simple maths will give the half-life but statistics would be needed to allow for uncertainty in all of the measurements made and to allow for the randomness of decays.
Wiki User
∙ 9y agoUsing a sample of the element of known size, measure the number of disintegrations happening in a known period of time. These numbers are then plugged into an equation, to calculate half life.
Wiki User
∙ 9y agoThe answer depends on what the question is!
Wiki User
∙ 13y agoamount of time it takes for half atoms of a radioactive isotope to decay
Wiki User
∙ 14y agohow many half-lives would it take for a sample of carbon-14 to be reduced to one over thirty two of it's oringinal mass?
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What is the best definition of half-life for a radioactive substance?
It indicates how long it takes for the material to decay.
Which element has the lowest half-life?
Bismuth has recently been found to have a no stable isotope and has a half-life of 4.6 x 10^19 years. Also, the simple hydrogen atom (a single proton), is theorized to decay at a rate of 6.6 x 10^33 years. So far all tests to observe a proton decay have failed.
How do you calculate the number of neutrons in boron?
For any element, subtract the atomic mass from the atomic number.
Is copper a stable element?
stableAnswer:Like many elements copper has many isotopes. Two of these are stable (63Cu and 65Cu) others are radioactive. The isotope with the longest half life is 67Cu with a half-life of almost 62 hours.
What is the half life of plastic?
Depends on what plastic, if any have half lifes at all :P
Does half life of any radioactive element decrease when its used?
The half-life can not be changed by any normal means.
If a radioactive element half life is 500000 years given 20 grams of the element how much is left after 4 half lives?
Just divide the original amount by 2, 4 times: 10; 5; 2.5; 1.25. The final number is the answer.
What is the best definition of half-life for a radioactive substance?
It indicates how long it takes for the material to decay.
What can element 117 do?
Element 117 was announced in January 2010, and it has a half life of around 0.078 seconds. It hasn't been studied enough for any of the properties to be determined.
How do you use the word half-life in a sentence?
"The radioactive decay of any atom is associated with the emission of a charged particle (alpha or positive or negative beta) from or the capture of an electron by the nucleus."Nucleonics Fundamentals by David B. Hoisington 1959; page 62.
What is radioactive half life of an element?
The half-life of a radioactive element is the time required for one-half of the nuclei of a radioisotope sample to decay to products.Half-life (t½) is the time required for a quantity to fall to half its value as measured at the beginning of the time period.
How do you shorten the half-life of a radioactive element?
Making any change in the half-life of an isotope of any element is generally something that lies outside our abilities. A very few radioactive materials have demonstrated a change in their half-lives when bathed in intense magnetic fields. Generally, however, the half-life on a given radionuclide is not something that can be changed. A number of experiments have been conducted wherein investigators have deliberately sought to influence radioactive half-life, but in all but the rarest cases, radionuclides are sublimely resistant to having their half-lives changed.
The rate of decay of a radioactive element is measured by its what?
Any of the following can be used: the half-life, or the mean lifetime, or the decay constant.Any of the following can be used: the half-life, or the mean lifetime, or the decay constant.Any of the following can be used: the half-life, or the mean lifetime, or the decay constant.Any of the following can be used: the half-life, or the mean lifetime, or the decay constant.
What is the half life of a radioistope?
The half-life of every isotope is different. Some elements and isotopes have half-lives in millions of years, while some elements have half-lives measured in milliseconds. You can look up all of the specifics for any element at webelements dot com.
What form is commonly found in nature?
The most stable of any element is found free in nature. Sometimes isotopes are also found along with the most stable of an element. Isotopes usually have short half life.
What would the percent of any element after two half lives?
25%
Radioactive decay can be affected by?
The rate of decay of a radioactive element cannot be influenced by any physical or chemical change. It is a rather constant phenomenon that appears to be independent of all others. The rate of decay is given by an element's half life, which is the amount of time for approximately half of the atoms to decay.
