Understanding the Randomness of Radioactive Decay

In summary: However, when you have a large enough sample, the randomness follows a predictable pattern, which is where the concept of half-life comes in. So while each individual decay may seem random, when looking at a large enough sample, the half-life remains constant.
  • #1
PrincePhoenix
Gold Member
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2
1-Half life is the time it takes for half of the nuclei in a sample of radioactive material to decay(Am I right?). Why does the first nucleas that decays,decay first and the one that decays in the end, decay in the end? What's the difference between the two nuclei or what causes this the nuclei to decay in different times?
2-Also if radioactivity occurs randomly in time and space (according to my book) then why does every radioactive isotope has its own constant half-life?
Thanks in advance for the answer.
 
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  • #2
PrincePhoenix said:
1-Half life is the time it takes for half of the nuclei in a sample of radioactive material to decay(Am I right?).
Correct.
Why does the first nucleas that decays,decay first and the one that decays in the end, decay in the end?
It's simply a 'random' process.
What's the difference between the two nuclei or what causes this the nuclei to decay in different times?
There is no discernible difference.

2-Also if radioactivity occurs randomly in time and space (according to my book) then why does every radioactive isotope has its own constant half-life?
Because each element/radionuclide has a unique set of protons and neutrons. If one looks at the 'chart of nuclides', one will see that there is a band (set) of nuclei that have long half-lives, and either side of the band, the half-lives are shorter, i.e. the radionuclides are less stable.
 
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  • #3
But you said it is a random process. Why does it have a specific half-life that is constant?
 
  • #4
PrincePhoenix said:
But you said it is a random process. Why does it have a specific half-life that is constant?
The specific half-life is related to the specific compostion, or unique number of protons and neutrons, which is alway the same for a given nuclide.
 
  • #5
At the present time, this is postulated rather than explained ... all we can do is "predict" the probability for any nucleus to decay during a given period of time, i.e. if we take 100,000 nuclei of a certain type, we can predict approximately how many of those will decay in one hour or one day. But we can't tell which ones specifically will decay. For all we know, they are all identical, even though some will decay and some will not. That is an example of a perfectly random process. (As opposed to a "pseudorandom" process, where the outcome is theoretically predictable, but we may have enough information to predict it - such as winning numbers in a lottery.)

From there to calculating a half life, it's a fairly straightforward mathematical computation.
 
  • #6
Thank You for explaining.
 
  • #7
PrincePhoenix said:
But you said it is a random process. Why does it have a specific half-life that is constant?
Collect 100 pennies, or other ubiquitous coin. toss them on the floor.

DO
pickup the "heads" and toss them on the floor
Loop until # "heads" = 0

Could you predict which pennies would be "heads"?
Could you predict how many times (half lives) you had to pick up the pennies before there were zero?
 
  • #8
With the coin analogy, each time you flip the heads, you are moving in steps. Is the theory for radioactive decay that it goes in steps or is it just such a perfectly random process that happens as a continuous process?
 
  • #9
tyrant91101 said:
With the coin analogy, each time you flip the heads, you are moving in steps. Is the theory for radioactive decay that it goes in steps or is it just such a perfectly random process that happens as a continuous process?

I think hamster answered that. It is a perfectly random process.
 

1. What is half life?

Half life is the amount of time it takes for half of a sample of a radioactive substance to decay into a more stable form. It is a characteristic property of each radioactive isotope and can range from fractions of a second to billions of years.

2. How is half life related to nuclear decay?

Nuclear decay is the process by which a radioactive nucleus spontaneously breaks apart, releasing energy and forming a new, more stable nucleus. Half life is the measure of how quickly this process occurs and can be used to predict the rate of decay for a given isotope.

3. How is half life used in radiometric dating?

In radiometric dating, the half life of a radioactive isotope is used to determine the age of a rock or other material. By measuring the amount of the isotope and its decay products, scientists can calculate how much time has passed since the material was formed.

4. Can half life be changed?

No, half life is a fixed property of a specific radioactive isotope and cannot be changed. It is determined by the nuclear structure of the isotope and cannot be altered by any physical or chemical means.

5. What are some real-life applications of half life and nuclear decay?

Half life and nuclear decay are used in a variety of fields, including medicine, geology, and environmental science. For example, radioactive isotopes can be used in medical imaging and cancer treatments, and the study of radioactive decay can help determine the age of fossils and geological formations. In addition, the half life of nuclear waste is an important consideration in the management of nuclear power plants.

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