How Does Half-Life Affect Remaining Mass of a Radioactive Isotope?

AI Thread Summary
The half-life of a radioactive isotope is defined as the time it takes for half of the original unstable nuclei to decay. In this discussion, a radioactive isotope with a half-life of 10 years and an initial mass of 12g is analyzed. After 10 years, the mass reduces to 6g, and after 20 years, it further reduces to 3g. The calculations confirm that after two half-lives, the remaining mass is indeed 3g. This illustrates the concept of half-life effectively in the context of radioactive decay.
dansics
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hello..im new to nuclear physics and i have problems attempting helf life questions.. hope you can help me with this question..

The half-life of a given radioactive isotope is 10 years. What is the mass of this isotope remaining undecayed after 20 years if the original mass was 12g? thank you..
 
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Welcome to PF, dansics. Please note that for homework questions, you need to show some work before we can help you, as per forum rules.

What is the definition of half life?
 
the defination of half-life is the time-taken for half the original unstable radioactive nuclei to decay.
 
Ok, so the question asks what mass is remaining after 20 years. How many half lives is this? What mass of the original isotope remains after one half life? From this can you say what mass remains after the number of half lives equivalent to 20 years?
 
emm..so in 10 years, the mass is reduced to 6 g and in 20 years the mass is then reduced to 3g?
Am i right?
 
Yup, you are correct.
 

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