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Ch.21 - Nuclear Chemistry
All textbooksBrown 15th EditionCh.21 - Nuclear ChemistryProblem 25
Chapter 21, Problem 25

Which of the following statements best explains why alpha emission is relatively common, but proton emission is extremely rare? (a) Alpha particles are very stable because of magic numbers of protons and neutrons. (b) Alpha particles occur in the nucleus. (c) Alpha particles are the nuclei of an inert gas. (d) An alpha particle has a higher charge than a proton.

Verified step by step guidance
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Step 1: Understand the nature of alpha particles. Alpha particles are helium nuclei, consisting of 2 protons and 2 neutrons, which makes them very stable due to the 'magic numbers' of protons and neutrons.
Step 2: Recognize the concept of 'magic numbers'. In nuclear physics, magic numbers refer to numbers of protons or neutrons that complete a shell within the nucleus, leading to extra stability.
Step 3: Compare the stability of alpha particles to protons. Alpha particles, being stable due to their composition, are more likely to be emitted from a nucleus than a single proton, which does not have the same inherent stability.
Step 4: Consider the role of nuclear forces. The strong nuclear force binds protons and neutrons in the nucleus. Alpha particles, with their balanced composition, are more favorably emitted than single protons, which would disrupt the nuclear balance.
Step 5: Evaluate the options. Option (a) highlights the stability of alpha particles due to magic numbers, which is a key reason for their common emission compared to the rarity of proton emission.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Alpha Emission

Alpha emission is a type of radioactive decay where an atomic nucleus emits an alpha particle, which consists of two protons and two neutrons. This process is common in heavy elements because the emission of an alpha particle helps the nucleus achieve a more stable configuration, often associated with 'magic numbers' of nucleons that confer additional stability.
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Alpha Decay

Proton Emission

Proton emission is a less common form of radioactive decay where a proton is ejected from the nucleus. This process is rare because it typically requires a nucleus to be in a highly unstable state, as removing a proton can significantly disrupt the balance of forces within the nucleus, making it less favorable compared to alpha emission.
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Neutron-Proton Ratio

Nuclear Stability

Nuclear stability is determined by the ratio of protons to neutrons and the overall binding energy of the nucleus. Nuclei with 'magic numbers' of protons and neutrons are particularly stable, which explains why alpha particles, which are composed of these stable configurations, are more commonly emitted than protons, which do not benefit from the same level of stability.
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Band of Stability: Nuclear Fission
Related Practice
Textbook Question

Despite the similarities in the chemical reactivity of elements in the lanthanide series, their abundances in Earth's crust vary by two orders of magnitude. This graph shows the relative abundance as a function of atomic number. Which of the following statements best explains the sawtooth variation across the series? (a) The elements with an odd atomic number lie above the belt of stability. (b) The elements with an odd atomic number lie below the belt of stability. (c) The elements with an even atomic number have a magic number of protons. (d) Pairs of protons have a special stability.

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Textbook Question

Which of the following nuclides would you expect to be radioactive: 5826Fe, 6027Co, 9241Nb, mercury-202, radium-226? Justify your choices.

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