Radon gas 222 86 Rn, is considered a serious health hazard. It decays by alpha e

Question

Radon gas 222 86 Rn, is considered a serious health hazard. It decays by alpha emission.

a) What is the daughter nucleus?

b) Is the daughter nucleus stable or radioactive? If the latter, how does it decay, and what is its half life?

c) Is the daughter nucleus also a noble gas, or is it chemically reactive?

d) Suppose 1.6 ng of 222 86 Rn seeps into a basement. What will be its activity? If the basement is then sealed, what will be the activity one month later?

Answers:

a) 218 84 Po

b) radioactive, alpha and beta decay, 3.1 min

c) Chemically reactive

d) 9.1x10^6 Bq, 4.0x10^4 Bq

Explanation / Answer

The equation for the alpha decay of 222Rn is: 222 86 Rn ----------> 218 84Po + 24He 1.Daughter nuleus is the one which came out and (218 84 Po). 2.wich is still radioactive (218 84 Po). When an atom decays by alpha emission that nucleus is actually undergoing fission and splits apart to give the alpha particle and a more stable nucleus with two less protons and two less neutrons. 84Po218 --> 2He4 + 82Pb214 half life of Po is : 3.10 minutes. It is fixed and you check in google. 3. Daughter nuleus is nobel gas element. The electron configuration of polonium is: [Xe]6s24f145d106p4. 4. When basement is not sealed.: 1.6ng of Rn starts decying according to first formulae. Half life of radon-222 (t1/2)= 3.8 days Time elapsed= One month = 30 days Therefore, no. of half lives elapsed (n) = 30/3.8= 7.89. Let the initial no. of atoms in the sample of Rn-222 be N0 Since the number of atoms present initially is proportional to the mass of the initial sample, N0= 1.6ng Therefore, amount of the sample left after 1 month , i.e 7.89 half lives= (1/2)^7.89

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