[Clean the question above and then proceed with classification]
Answer (1)
Alpha decay results in a decrease of 4 in mass number and 2 in atomic number.
To find the parent nucleus, add 4 to the mass number and 2 to the atomic number of the daughter nucleus ( 208 P b ).
The parent nucleus has a mass number of 208 + 4 = 212 and an atomic number of 82 + 2 = 84 .
The element with atomic number 84 is Polonium (Po), so the parent nucleus is 212 P o .
Explanation
Understanding Alpha Decay 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. We need to determine the parent nucleus that undergoes alpha decay to produce 208 P b .
Determining the Parent Nucleus In alpha decay, the mass number (A) decreases by 4, and the atomic number (Z) decreases by 2. Therefore, to find the parent nucleus, we need to reverse this process. We add 4 to the mass number of 208 P b and 2 to its atomic number.
Calculating Mass and Atomic Numbers The atomic number of Lead (Pb) is 82. So, the parent nucleus will have: Mass number: 208 + 4 = 212 Atomic number: 82 + 2 = 84
Identifying the Parent Element The element with atomic number 84 is Polonium (Po). Therefore, the parent nucleus is 212 P o .
Writing the Decay Equation The alpha decay can be represented as: 212 P o → 208 P b + 4 He
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 real-world applications. For instance, smoke detectors use americium-241, which undergoes alpha decay to produce alpha particles. These particles ionize the air inside the detector, creating a current. When smoke enters the detector, it disrupts this current, triggering the alarm. Understanding alpha decay helps in designing and improving such safety devices, ensuring they function effectively to protect lives and property. The ability to predict the products of alpha decay is crucial in various fields, including nuclear medicine for targeted therapies and in assessing the safety of nuclear materials.
