Chapter 33: Problem 41
The number of \(\beta\) -particles, if a radioactive element \(90^{238}\) decays into \({ }_{83} Y^{222}\) is : (a) 4 (b) 6 (c) 2 (d) 1
Short Answer
Expert verified
The number of \( \beta \)-particles emitted is 1.
Step by step solution
01
Analyze the given decay process
In the given problem, the radioactive element starts as \( {}^{238}_{90}X \) and decays to \( {}^{222}_{83}Y \). Here, \( X \) is the parent isotope, and \( Y \) is the daughter isotope.
02
Define the decay equations
During radioactive decay, the nucleus can undergo alpha or beta decay: \( \alpha \)-particles have a mass number of 4 and an atomic number of 2, while \( \beta \)-particles do not change the mass number but change the atomic number by \( +1 \).
03
Calculate mass number changes
Start with the mass number: \( 238 \to 222 \). The loss in mass number is \( 238 - 222 = 16 \). Each \( \alpha \)-particle decreases the mass number by 4, therefore number of \( \alpha \)-particles emitted: \( \frac{16}{4} = 4 \).
04
Calculate atomic number changes
The initial atomic number is 90 and the final is 83. The change in atomic number is \( 90 - 83 = 7 \). Given that each \( \alpha \)-particle decreases the atomic number by 2, hence loss due to 4 \( \alpha \)-particles: \( 4 \times 2 = 8 \).
05
Determine the number of beta particles
After accounting for reduction due to \( \alpha \)-particles, the change in atomic number needing adjustment by \( \beta \)-particles is \( 7 - 8 = -1 \). As each \( \beta \)-particle increases the atomic number by 1, 1 \( \beta \)-particle is emitted to adjust for this.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Alpha Decay
In alpha decay, a radioactive nucleus emits an alpha particle, which is identical to a helium nucleus. It consists of two protons and two neutrons. This accounts for a reduction in mass number by 4 and a decrease in the atomic number by 2.
When a nucleus like \( {}^{238}_{90}X \) undergoes alpha decay, the transformation leads to a new element with reduced atomic number and mass number.
It is a type of decay that especially stabilizes large nuclei that may have too many protons clustered together.
When a nucleus like \( {}^{238}_{90}X \) undergoes alpha decay, the transformation leads to a new element with reduced atomic number and mass number.
- Example: The emission of an alpha particle from \( {}^{238}_{90}X \) reduces its mass number to 234 and atomic number to 88.
- As a result: \({}^{234}_{88}Y\) is formed.
It is a type of decay that especially stabilizes large nuclei that may have too many protons clustered together.
Beta Decay
Beta decay is an interesting process where a neutron in the nucleus turns into a proton, or vice versa, emitting a beta particle in the process. This beta particle is simply a high-energy, high-speed electron or positron.
In the exercise, beta decay increases the atomic number by 1 while the mass number remains unchanged.
The beta decay process ensured that the final atomic number was as specified in the exercise, \( {}_{83}Y^{222} \).
In the exercise, beta decay increases the atomic number by 1 while the mass number remains unchanged.
- Important Note: In beta-minus decay, a neutron turns into a proton, thereby increasing the atomic number.
- For beta-plus decay, a proton turns into a neutron, resulting in a decrease of the atomic number.
The beta decay process ensured that the final atomic number was as specified in the exercise, \( {}_{83}Y^{222} \).
Mass and Atomic Number Calculations
Understanding the calculations for mass and atomic numbers is crucial in nuclear decay problems. Each decay mode affects these numbers differently.In the provided exercise:
Practicing such calculations builds a strong conceptual framework for tackling more complex nuclear decay problems.
- The initial mass number was 238, while the final number is 222. The difference, 16, results from the emission of four alpha particles \( (4 \times 4 = 16) \).
- The atomic number changed from 90 to 83. The emission of four alpha particles leads to a reduction by 8 \( (4 \times 2 = 8) \), resulting in a need to adjust back by +1 via one beta particle emission \((+1)\).
Practicing such calculations builds a strong conceptual framework for tackling more complex nuclear decay problems.