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Isotopes of plutonium

Isotopes of plutonium is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Isotopes of plutonium rather than just read about it. In short: Plutonium (94Pu) is an artificial element, except for trace quantities resulting from neutron capture by uranium, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes.

Isotopes of plutonium — main illustration
Isotopes of plutonium — illustration

Key takeaways

  • Isotopes of plutonium belongs to chemistry; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Isotopes of plutonium to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Isotopes of plutonium from memory before moving on to harder problems.

Reference excerpt

Plutonium (94Pu) is an artificial element, except for trace quantities resulting from neutron capture by uranium, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes. It was synthesized before being found in nature, with the first isotope synthesized being 238Pu in 1940. Twenty-two plutonium radioisotopes have been characterized. The most stable are 244Pu with a half-life of 81.3 million years, 242Pu with a half-life of 375,000 years, 239Pu with a half-life of 24,110 years, and 240Pu with a half-life of 6,561 years. This element also has eight meta states; all have half-lives of less than one second. The known isotopes of plutonium range from 226Pu to 247Pu. The primary decay modes before the most stable isotope, 244Pu, are spontaneous fission and alpha decay; the primary mode after is beta emission. The primary decay products before 244Pu are isotopes of uranium and neptunium (not considering fission products), and the primary decay products after are isotopes of americium.

List of isotopes

Actinides vs fission products

Notable isotopes Plutonium-238 has a half-life of 87.74 years and emits alpha particles. Pure 238Pu for radioisotope thermoelectric generators that power some spacecraft is produced by neutron capture on neptunium-237 but plutonium from spent nuclear fuel can contain as much as a few percent 238Pu, originating from 237Np, alpha decay of 242Cm, or (n,2n) reactions. Plutonium-239 has half-life 24,100 years. 239Pu and 241Pu are fissile; meaning their nuclei can split by being bombarded by slow thermal neutrons, releasing energy, gamma radiation and more neutrons. It can therefore sustain a nuclear chain reaction, leading to applications in nuclear weapons and nuclear reactors. 239Pu is synthesized by irradiating uranium-238 with neutrons in a nuclear reactor, then recovered via nuclear reprocessing of the fuel. Further neutron capture produces successively heavier isotopes. Plutonium-240 has a high rate of spontaneous fission, raising the background neutron radiation of plutonium. Plutonium is graded by proportion of 240Pu: weapons grade (<7%), fuel grade (7–19%) and reactor grade (>19%). Lower grades are less suited for bombs and thermal reactors but can fuel fast reactors. Plutonium-241 is fissile, but beta decays with a half-life of 14 years to americium-241. Plutonium-242 is not fissile, nor very fertile (requiring 3 more neutron captures to become fissile); and has a low neutron capture cross section, and a longer half-life than any of the lighter isotopes. Plutonium-244 is the most stable isotope of plutonium, with a half-life of about 80 million years. It is not significantly produced in nuclear reactors because 243Pu has a short half-life, but some is produced in nuclear explosions. 244Pu has been found in interstellar space and has the second longest half-life of any non-primordial radioisotope.

Production and uses

… excerpt ends here. Continue reading the full article.

Illustrations

Isotopes of plutonium: Transmutation flow between 238Pu and 244Cm in LWR.[19]Transmutation speed not shown and varies greatly by nuclide. 245Cm–248Cm are long-lived with negligible decay.
Transmutation flow between 238Pu and 244Cm in LWR.[19]Transmutation speed not shown and varies greatly by nuclide. 245Cm–248Cm are long-lived with negligible decay.
Isotopes of plutonium: A 5.3 kg ring of weapons-grade electrorefined plutonium, 99.96% purity. This is enough plutonium for an efficient nuclear weapon. The ring shape is needed to depart from a spherical shape and avoid criticality.
A 5.3 kg ring of weapons-grade electrorefined plutonium, 99.96% purity. This is enough plutonium for an efficient nuclear weapon. The ring shape is needed to depart from a spherical shape and avoid criticality.

Worked examples

Example 1 — a first encounter with Isotopes of plutonium

Start with the simplest possible case. Write down what Isotopes of plutonium claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Isotopes of plutonium before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Isotopes of plutonium ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Isotopes of plutonium

In research
Isotopes of plutonium appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Isotopes of plutonium in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Isotopes of plutonium is common in secondary-school and first-year university syllabi. It links to neighbouring topics Isotopes of plutonium, Lists of isotopes by element, Plutonium, so understanding it makes those chapters shorter.
In everyday life
Look for Isotopes of plutonium outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Isotopes of plutonium in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Isotopes of plutonium means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Isotopes of plutonium out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Isotopes of plutonium in simple terms?

Plutonium (94Pu) is an artificial element, except for trace quantities resulting from neutron capture by uranium, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no stable isotopes.

Why does Isotopes of plutonium matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Isotopes of plutonium?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Isotopes of plutonium.

Tags

  • Isotopes of plutonium
  • Lists of isotopes by element
  • Plutonium

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