[Clean the question above and then proceed with classification]
Answer (2)
Identify that alpha decay results in a decrease of 4 in mass number and 2 in atomic number.
Determine the atomic number of Lead (Pb) is 82.
Calculate the parent nucleus's atomic number by adding 2 to Lead's atomic number: 82 + 2 = 84 , and its mass number by adding 4 to Lead's mass number: 208 + 4 = 212 .
Identify the element with atomic number 84 as Polonium (Po), thus the parent nucleus is 212 P o .
Explanation
Understanding the Problem The problem states that an alpha decay results in the production of Lead-208 ( 208 P b ). Alpha decay involves the emission of an alpha particle (which is a helium nucleus, 4 He ) from a parent nucleus, transforming it into a daughter nucleus. In this case, 208 P b is the daughter nucleus. The task is to determine the parent nucleus that undergoes alpha decay to produce 208 P b .
Finding the Parent Nucleus To find the parent nucleus, we need to reverse the alpha decay process. Alpha decay reduces the mass number (A) by 4 and the atomic number (Z) by 2. Therefore, to find the parent nucleus, we must add 4 to the mass number of 208 P b and 2 to its atomic number.
Determining Atomic and Mass Numbers Lead (Pb) has an atomic number of 82. Therefore, the parent nucleus will have:
Atomic number: 82 + 2 = 84 Mass number: 208 + 4 = 212
The element with atomic number 84 is Polonium (Po). Therefore, the parent nucleus is 212 P o .
Representing the Alpha Decay The alpha decay can be represented as:
212 P o → 208 P b + 4 He
This equation shows that Polonium-212 decays into Lead-208 by emitting an alpha particle.
Final Answer Therefore, the parent nucleus that undergoes alpha decay to produce 208 P b is 212 P o .
Examples
Alpha decay is a fundamental concept in nuclear physics with practical applications in various fields. For instance, smoke detectors use the alpha decay of Americium-241 to create a current; when smoke particles interfere with this current, the alarm is triggered. Understanding alpha decay also helps in nuclear medicine, where certain isotopes that undergo alpha decay are used in targeted cancer therapies, delivering radiation directly to cancer cells. Moreover, geologists use alpha decay to determine the age of rocks through radiometric dating techniques, such as uranium-lead dating.
The parent nucleus that undergoes alpha decay to produce Lead-208 ( 208 P b ) is Polonium-212 ( 212 P o ). This is calculated by adding 2 to the atomic number and 4 to the mass number of Lead. Therefore, the alpha decay can be written as ${ }^{212}Po \rightarrow { }^{208}Pb + { }^{4}He.
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