chemistry

Lanthanum(III) iodide

Lanthanum(III) iodide 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 Lanthanum(III) iodide rather than just read about it. In short: Lanthanum(III) iodide is an inorganic compound containing lanthanum and iodine with the chemical formula LaI3. Synthesis Lanthanum(III) iodide can be synthesised by the reaction of lanthanum metal with mercury(II) iodide: 2 La + 3 HgI2 → 2 LaI3 + 3 Hg It can also be prepared from the elements, that is by the reaction of metallic lanthanum with iodine: 2 La + 3 I2 → 2 LaI3 While lanthanum(III) iodide solutions can be…

Key takeaways

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

Reference excerpt

Lanthanum(III) iodide is an inorganic compound containing lanthanum and iodine with the chemical formula LaI3.

Synthesis Lanthanum(III) iodide can be synthesised by the reaction of lanthanum metal with mercury(II) iodide:

2 La + 3 HgI2 → 2 LaI3 + 3 Hg It can also be prepared from the elements, that is by the reaction of metallic lanthanum with iodine:

2 La + 3 I2 → 2 LaI3 While lanthanum(III) iodide solutions can be generated by dissolving lanthanum oxide in hydroiodic acid, the product will hydrolyse and form polymeric hydroxy species:

La2O3 + 6 HI → 2 LaI3 + 3 H2O → further reactions

Structure Lanthanum(III) iodide adopts the same crystal structure as plutonium(III) bromide, with 8-coordinate metal centres arranged in layers. This orthorhombic structure is typical of the triiodides of the lighter lanthanides (La–Nd), whereas heavier lanthanides tend to adopt the hexagonal bismuth(III) iodide structure.

Reactivity and applications Lanthanum(III) iodide is very soluble in water and is deliquescent. Anhydrous lanthanum(III) iodide reacts with tetrahydrofuran to form a photoluminescent complex, LaI3(THF)4, with an average La–I bond length of 3.16 Å. This complex is a starting material for amide and cyclopentadienyl complexes of lanthanum.

Related compounds Lanthanum also forms a diiodide, LaI2. It is an electride and is best formulated {LaIII,2I−,e−}, with the electron delocalised in a conduction band. Several other lanthanides form similar compounds, including CeI2, PrI2 and GdI2. Lanthanum diiodide adopts the same tetragonal crystal structure as PrI2. Lanthanum(III) iodide reacts with lanthanum metal under an argon atmosphere in a tantalum capsule at 1225 K to form the mixed-valence compound La2I5. Reduction of LaI2 or LaI3 with metallic sodium in an argon atmosphere at 550 °C gives lanthanum monoiodide, LaI, which has a hexagonal crystal structure.

References

Illustrations

Worked examples

Example 1 — a first encounter with Lanthanum(III) iodide

Start with the simplest possible case. Write down what Lanthanum(III) iodide 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 Lanthanum(III) iodide 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 Lanthanum(III) iodide 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 Lanthanum(III) iodide

In research: Lanthanum(III) iodide 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 Lanthanum(III) iodide 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: Lanthanum(III) iodide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Inorganic compounds, Iodides, Lanthanide halides, so understanding it makes those chapters shorter.
In everyday life: Look for Lanthanum(III) iodide 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 Lanthanum(III) iodide in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lanthanum(III) iodide 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 Lanthanum(III) iodide out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lanthanum(III) iodide in simple terms?

Lanthanum(III) iodide is an inorganic compound containing lanthanum and iodine with the chemical formula LaI3. Synthesis Lanthanum(III) iodide can be synthesised by the reaction of lanthanum metal with mercury(II) iodide: 2 La + 3 HgI2 → 2 LaI3 + 3 Hg It can also be prepared from the elements, that…

Why does Lanthanum(III) iodide 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 Lanthanum(III) iodide?

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 Lanthanum(III) iodide.