uranium 235
C1Formal, Technical, Scientific
Definition
Meaning
A specific radioactive isotope of uranium with an atomic mass of 235, capable of sustaining a nuclear fission chain reaction.
The fissile material used as the primary fuel in nuclear reactors and atomic weapons, distinguished from the more abundant isotope uranium-238 by its ability to undergo fission with thermal neutrons.
Linguistics
Semantic Notes
The term refers strictly to a scientific entity (an isotope). It is often used in a broader geopolitical and military context to discuss nuclear energy, proliferation, and weaponry. It is typically written with a hyphen (uranium-235) in formal scientific texts, but the space is also common.
Dialectal Variation
British vs American Usage
Differences
No significant lexical or grammatical differences. Pronunciation may differ slightly.
Connotations
Identical technical connotations. In political discourse, it carries the same weight regarding nuclear energy and weapons.
Frequency
Equally low-frequency and specialized in both dialects, confined to scientific, engineering, political, and historical contexts.
Vocabulary
Collocations
Grammar
Valency Patterns
[enrich/separate/use] + uranium 235uranium 235 + [is used/fissions/decays][isotope/element/fuel] + of + uranium 235Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “[No common idioms for this specific scientific term]”
Usage
Context Usage
Business
In the context of the nuclear energy industry and commodity trading of enriched fuel.
Academic
Core term in nuclear physics, chemistry, engineering, and modern history papers.
Everyday
Virtually never used in casual conversation; appears in news about nuclear power or weapons.
Technical
Precise term in nuclear reactor design, weapons manufacturing, isotopic separation processes, and radiation physics.
Examples
By Part of Speech
verb
British English
- [Not applicable as a verb]
American English
- [Not applicable as a verb]
adverb
British English
- [Not applicable as an adverb]
American English
- [Not applicable as an adverb]
adjective
British English
- The uranium-235 component must be carefully measured.
- They analysed the uranium 235 sample.
American English
- The uranium-235 content was too low for a weapon.
- A uranium 235 core is required for this design.
Examples
By CEFR Level
- Uranium 235 is a special kind of metal.
- This element is very important for energy.
- Nuclear power plants often use uranium 235 as fuel.
- Scientists can separate uranium 235 from other types of uranium.
- The enrichment process increases the concentration of uranium-235 in the nuclear fuel.
- Unlike uranium-238, uranium-235 is fissionable and can sustain a chain reaction.
- The geopolitical implications of a nation acquiring weapons-grade uranium-235 are profound and often trigger international sanctions.
- Precise neutron cross-section measurements for uranium-235 are critical for the design of advanced nuclear reactors.
Learning
Memory Aids
Mnemonic
Think of the atomic bomb 'Little Boy' dropped on Hiroshima: its core was made of **Uranium 235**. 2+3+5 = 10, and it takes a critical mass of about 10+ kg to start a chain reaction.
Conceptual Metaphor
URANIUM 235 IS A KEY (to unlocking atomic energy); URANIUM 235 IS A THRESHOLD (to the nuclear age).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Do not translate as 'уран 235ый' – the correct form is 'уран-235' (uran-235).
- Be aware that in Russian technical contexts, it may be referred to simply as '235-й изотоп' (235th isotope) when the context is clear.
Common Mistakes
- Pronouncing it as 'uranium two hundred thirty-five'. It is always 'uranium two thirty-five'.
- Writing it as 'Uranium 235' with a capital U mid-sentence (only 'Uranium' at the start of a sentence).
- Confusing it with 'plutonium-239', which is a different fissile material.
Practice
Quiz
What is the primary characteristic that distinguishes uranium-235 from uranium-238?
FAQ
Frequently Asked Questions
Yes, but it is rare. Naturally occurring uranium is over 99% uranium-238, with only about 0.7% being the fissile uranium-235.
Its nucleus can split (fission) when struck by a slow-moving neutron, releasing a tremendous amount of energy and more neutrons, which can then split other atoms in a sustained chain reaction.
Enrichment is the industrial process of increasing the percentage of uranium-235 in a sample of uranium. Natural uranium (0.7% U-235) is enriched to around 3-5% for reactor fuel or over 90% for weapons.
Yes, it is radioactive and poses both radiological and criticality hazards. It must be handled with extreme care using specialised shielding and protocols to prevent accidental nuclear chain reactions.