Question

1. What is natural radioactivity? Speak to the different types of radiation that an unstable nucleus may emit, and the different types of radiation involved.
2. Why is it important to be able to write a balanced nuclear equation for radioactive decay? Go into some of the specifics of what is involved in writing an equation.
3. What is a “half-life” and why is it important to know the half-life of a radioisotope? List a few applications of how scientists make use of having this knowledge. Why would it be so important to know the half-lives of radioisotopes when it comes to medical applications?
4. Briefly describe how we can make use our knowledge of radioactivity in medicine. Speak about the characteristics of the radioisotopes used in these types of applications. What might they have in common? What process(es) do we use to detect these radioisotopes?

Answer 1

Answer(a) Natural Radioactivity is the phenomenon of natural disintegration of radioactive substance in order to stabilize their nuclei to stable nuclei. For example an isotope of carbon that is C-14, undergoes natural radioactivity.

The different type of radiation involved during radioactive phenomenon are radiation of alpha rays, beta rays and gamma rays these are mainly radiated but beside these rays X-rays and neutron rays are also emitted these emissions takes place to counter the surplus energy.

Answer(b) It is important to write the balanced chemical equation for the radioactive decay because we know that the unstable nuclei tend to the stable nuclei which is accompanied by the radiation of Alpha rays, beta rays and gamma rays

When alpha decay takes place

₉₂U²³⁸ =   ₂He⁴ + ₉₀Th²³⁴ ( this decay is accompanied by the alpha rays,where alpha is similar to the He nuclei and the parent atom i. e. U(234) after decay changes into Thoruum which is different and new element also known as daughter atom in this decay.

When beta decays takes place

₉₀Th²³⁴ =  _-1⁰ + ₉₁Pa²³⁴ (this decay is accompanied by the beta rays and this decay takes place then the atomic no of daughter element increases by 1 from parent element)

When decay takes place then there is no change in either mass no or atomic no so there is no change in the element remains the same.

So, from above discussion it is clear that balanced equation help us to find the no particle radiated and the new element formed.

Answer(c) Half life period of a radioactive substance is defined as the time period in which it becomes the half of the initial amount of the radioactive substance. t_½ = 0.693/k

Where k is disintegration constant

t_½ is half life period.

It is important to know the half life of radioactive isotope so that we can easily calculate the amount of radioactive substance remaining after the no of half life period.

Carbon 14 dating is one of the best example of it because after the death of organism ¹⁴C reverts into ¹⁴N and the half life is 5370years(so in case if an organism is having 5gm of ¹⁴C and the present amount is 0.625gm of it now wecan easily calculate the that orgasm has gone through 3 half life so organism was alive 16110 years ago).

Radioisotopes are used to follow the paths of biochemical reactions or to determine how a substance is distributed within an organism for example ⁶⁰Co is used as therapy to prevent cancer.