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Verified answer
The istopes and that's it.
The half-life of a radioactive substance decreases as it decays. As the substance decays, the amount of radioactive material decreases, leading to a shorter time period for half of the material to decay. This results in a shorter half-life over time.
For a given isotope of a given element, the half-life is generally considered to be a constant. But there is more.
Different isotopes of different elements have unique half-lives. The half-life for a given element is based on the constituent isotopes in a sample: different isotopes of the same element can vary greatly in their half-lives.
It is the configuration of the nucleus which means it is either stable or unstable, giving rise to radioactive decay. Essentially it is the balance of the forces within the nucleus, between the protons and neutrons in it, that determines this. Thus you can have a stable nucleus of an element but adding another neutron upsets this and produces instability.
There are so many different radioisotopes it would take an encyclopedia to describe them all. What can definitely be said is that once a radioisotope is formed, its activity will follow the half-life curve regardless of external conditions such as temperature. The only way to change it is to irradiate it again in a reactor (neutron flux) to access the nucleus itself.
The half-life of any particular radioactive substance (isotope) is constant. It does not change as it decays. However, when decay does occur, there is a tendency to form other radioactive isotopes, what we call daughter products, and those can and do have their own half-lives. This, of course, complicates the measure of half-life, and forces analysis of energy levels and other chemical properties, i.e. not just count rate, in order to assess activity and its related half-life.
"Time required to reach the initial concentration oe a reactant to it half value is called half life period."
What are "the following"? However half life is a property of a particular isotope and can't be changed for that one, so the only way to change it is to convert it to a different isotope by neutron irradiation.
the type of isotope
In general, and at temperatures one might commonly find on Earth, temperature has
no appreciable effect on half life. If the temperature of an atom is elevated sufficiently,
we can get effects in which the question of half life becomes moot, because the atom is
no longer able to hold together in atomic form, but I am supposing that is not what this
question is about. There are certain circumstances, under which the half life might be
affected by temperatures that a person might consider more ordinary. One such place is
in a neutron rich environment, such as in the core of a nuclear reactor. Neutrons colliding
with the nuclei of atoms can cause the atom to become a different isotope of the same
element, to decay, or to undergo fission. The probability of the neutron colliding with the
nucleus depends on what is called the "nuclear cross section" which is measured in a unit
called a "barn." The nuclear cross section generally increases with temperature, though as
the temperature increases, the actual value goes up and down, depending on the
temperature and the specific isotope involved. So, in a neutron rich environment,
increasing the temperature generally reduces the half life.
All very interesting, I'm sure. Now, let me attempt an answer to the question:
For a large enough sample with enough atoms in it, the half-life doesn't change
as time passes and the atoms in the sample decay. If the half-life depended on
how much of the original sample remains, then there wouldn't be any such thing
as the 'half life' of a radioactive substance at all. It would have to be "the half-life
of this substance after 30 percent of it has already decayed" or some such number.
But you never see that. You only see "the half-life of this substance", and it doesn't
matter how much of it you start with, or how much of the original sample has already
decayed.
For a nucleus stationary by your side, nothing whatsoever. However, if the nucleus is passing you near the speed of light, relativistic effects will make the halflife seem to increase.
What is the percentage of radioactive nuclei left after 3 half lives have passed?
12.5%
What is the half life of a radioactive substance if 2.4G decays to 1.80G in 66 hours?
The half-life of the radioactive substance is approximately 33 hours. This can be determined by observing that half of the initial amount decays in 33 hours, and the same applies to subsequent half-lives.
Can the half life of a radioactive isotope decrease as the isotope decays?
No, the half-life of a radioactive isotope is a constant property of that particular isotope and does not change as it decays. The half-life is defined as the time it takes for half of the atoms in a sample to decay. Once set, the half-life remains constant regardless of how many atoms have decayed.
How is radioactivity and half life related?
Radioactivity is the process by which unstable atomic nuclei release energy in the form of radiation. Half-life is the time it takes for half of a radioactive substance to decay. The concept of half-life is used to measure the rate at which a radioactive substance decays and is a key parameter in understanding and monitoring radioactivity.
What fraction of a radioactive sample decays after three half lives?
If I take a radioactive sample of 400 moles of an unknown substance and let it decay to the point of three half-lives I would have 50 moles left of the sample. 1/2 of what is left will decay in the next half-life. At the end of that half-life I will have 25 moles left of the unknown substance or 4/25.
What is the percentage of radioactive nuclei left after 3 half lives have passed?
12.5%
What happens to radioactive materials if you do not use them?
That depends on the radioactive material. But whether you use it or not, the radioactive material will decay into other elements over the course of time. The time it takes for half of the material to decay into something else is called the "half-life". The more radioactive the substance is, the faster it decays. The half-life of a radioactive element can be measured from fractions of a second to billions of years.
What is the half life of a radioactive substance if 2.4G decays to 1.80G in 66 hours?
The half-life of the radioactive substance is approximately 33 hours. This can be determined by observing that half of the initial amount decays in 33 hours, and the same applies to subsequent half-lives.
What happens to the half life as the sample gets older?
The half-life remains constant for a particular radioactive substance, regardless of how old the sample is. This means that the rate at which the substance decays and the time it takes for half of it to decay remains consistent over time.
Which information can be determined using half-life?
Half-life can be used to determine the rate at which a radioactive substance decays over time, to calculate the amount of time for half of the substance to decay, and to estimate the remaining quantity of the substance after a certain period.
What is radioactive half-life used for?
Radioactive half-life is used to measure the rate at which a radioactive substance decays. It is important in determining the amount of time it takes for half of a radioactive substance to decay into a stable form. This information is useful in various fields such as medicine, environmental science, and geology for dating purposes and evaluating risks associated with radioactive materials.
Can the half life of a radioactive isotope decrease as the isotope decays?
No, the half-life of a radioactive isotope is a constant property of that particular isotope and does not change as it decays. The half-life is defined as the time it takes for half of the atoms in a sample to decay. Once set, the half-life remains constant regardless of how many atoms have decayed.
How is radioactivity and half life related?
Radioactivity is the process by which unstable atomic nuclei release energy in the form of radiation. Half-life is the time it takes for half of a radioactive substance to decay. The concept of half-life is used to measure the rate at which a radioactive substance decays and is a key parameter in understanding and monitoring radioactivity.
What is the sample of the radioactive isotope 131I decays its half-life?
The sample of radioactive isotope 131I decays over its half-life of approximately 8 days. This means that within 8 days, half of the initial amount of 131I will decay through radioactive decay.
What affect the half life of a radioactive substance A the mass of the substance B the temperature of the substance C the addition of a catalyst D the type?
A. The half-life of a radioactive substance is determined by the specific decay process of that substance, so it is not affected by the mass of the substance or the temperature. B. The mass of the substance does not affect the half-life of a radioactive substance. C. The addition of a catalyst does not affect the half-life of a radioactive substance. D. The type of radioactive substance directly determines its half-life, as different substances undergo radioactive decay at varying rates.
Best definition of half-life for a radioactive substance?
The half-life of a radioactive substance is the time it takes for half of the atoms in a sample to decay. It is a constant characteristic of each radioactive isotope. After one half-life, half of the original substance will remain, and the other half will have decayed into other elements.
What fraction of a radioactive sample decays after three half lives?
If I take a radioactive sample of 400 moles of an unknown substance and let it decay to the point of three half-lives I would have 50 moles left of the sample. 1/2 of what is left will decay in the next half-life. At the end of that half-life I will have 25 moles left of the unknown substance or 4/25.
