Isotopes of uranium

Question

Isotopes of uranium

Examoogle · Accepted Answer

All of the above

Explanation: Uranium exists in nature primarily as a mixture of three isotopes: $^{234}U$, $^{235}U$, and $^{238}U$. These isotopes share the same atomic number (92) but differ in the number of neutrons in their nuclei, resulting in different mass numbers.

Working Principle: Isotopes are atoms of the same element with identical electronic configurations, meaning they exhibit similar chemical properties. However, the difference in mass (due to the number of neutrons) leads to variations in physical properties and nuclear stability. $^{235}U$ is unique because it is fissile, meaning it can sustain a nuclear chain reaction, while $^{238}U$ is fertile and makes up the vast majority of natural uranium.

Key Formulas: $N_n = A - Z$ — where $N_n$ is the number of neutrons, $A$ is the atomic mass number, and $Z$ is the atomic number.; $^{235}_{92}U$ — specific representation of the fissile isotope used in nuclear reactors.

Key Points: $^{238}U$ comprises approximately 99.27% of natural uranium.; $^{235}U$ comprises approximately 0.72% of natural uranium.; $^{234}U$ is a decay product of $^{238}U$ and exists in trace amounts (approx. 0.005%).; Fissile material is required to initiate and maintain a self-sustaining chain reaction in a thermal nuclear reactor.

Advantages: Nuclear fuel provides extremely high energy density compared to fossil fuels.; Controlled fission of $^{235}U$ generates massive amounts of heat for steam production.

Disadvantages: Radioactive waste management is required for long-term safety.; Uranium enrichment is a complex and highly sensitive industrial process.

Applications: Nuclear power generation via fission reactors.; Radioisotopic dating and medical research.

Additional Info: The atomic number of Uranium is always 92; the variation occurs only in the mass number (A).. Options A, B, and C represent the three naturally occurring isotopes of Uranium, thus Option D is the correct inclusion of all.

Answer: D is correct — All listed isotopes ($^{235}U$, $^{234}U$, and $^{238}U$) are naturally occurring isotopes of the element Uranium.

Exam Tip: In competitive exams, remember that $^{235}U$ is the only naturally occurring fissile isotope; others like $^{233}U$ or $^{239}Pu$ are usually man-made through transmutation.

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