chemistry

Isotopes of lanthanum

Isotopes of lanthanum 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 lanthanum rather than just read about it. In short: Naturally occurring lanthanum (57La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.911% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being 138La, with a half-life of 1.03×1011 years; 137La, with a half-life of 60,000 years and 140La, with a half-life of 40.289 hours.

Key takeaways

Isotopes of lanthanum 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 lanthanum to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Isotopes of lanthanum from memory before moving on to harder problems.

Reference excerpt

Naturally occurring lanthanum (57La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.911% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being 138La, with a half-life of 1.03×1011 years; 137La, with a half-life of 60,000 years and 140La, with a half-life of 40.289 hours. The remaining radioactive isotopes have half-lives that are less than a day and the majority of these less than a minute. This element also has 12 nuclear isomers, the longest-lived of which is 132mLa, with a half-life of 24.3 minutes. Lighter isotopes mostly decay to isotopes of barium and heavy ones mostly decay to isotopes of cerium. 138La can decay to both. The known isotopes of lanthanum range from 116La to 155La.

List of isotopes

See also Daughter products other than lanthanum

Isotopes of cerium Isotopes of barium Isotopes of caesium

References

Isotope masses from: Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001 Isotopic compositions and standard atomic masses from: de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry. 75 (6): 683–800. doi:10.1351/pac200375060683. Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry. 78 (11): 2051–2066. doi:10.1351/pac200678112051. "News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005. Half-life, spin, and isomer data selected from the following sources. Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001 National Nuclear Data Center. "NuDat 3.0 database". Brookhaven National Laboratory. Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

Illustrations

Worked examples

Example 1 — a first encounter with Isotopes of lanthanum

Start with the simplest possible case. Write down what Isotopes of lanthanum 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 lanthanum 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 lanthanum 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 lanthanum

In research: Isotopes of lanthanum 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 lanthanum 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 lanthanum is common in secondary-school and first-year university syllabi. It links to neighbouring topics Isotopes of lanthanum, Lanthanum, Lists of isotopes by element, so understanding it makes those chapters shorter.
In everyday life: Look for Isotopes of lanthanum 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 lanthanum in 20 minutes

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

Frequently asked questions

What is Isotopes of lanthanum in simple terms?

Why does Isotopes of lanthanum 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 lanthanum?

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 lanthanum.