chemistry

Terbium compounds

Terbium compounds 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 Terbium compounds rather than just read about it. In short: Terbium compounds are compounds formed by the lanthanide metal terbium (Tb). Terbium generally exhibits the +3 oxidation state in these compounds, such as in TbCl3, Tb(NO3)3 and Tb(CH3COO)3.

Key takeaways

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

Reference excerpt

Terbium compounds are compounds formed by the lanthanide metal terbium (Tb). Terbium generally exhibits the +3 oxidation state in these compounds, such as in TbCl3, Tb(NO3)3 and Tb(CH3COO)3. Compounds with terbium in the +4 oxidation state are also known, such as TbO2 and BaTbF6. Terbium can also form compounds in the 0, +1 and +2 oxidation states. The trivalent terbium ion (Tb3+) is generally colorless in aqueous solution, and when it is irradiated by certain wavelengths of ultraviolet light (such as 254 nm or 365 nm) in solution or crystal form, it will emit green fluorescence. This property has given rise to applications in fields such as optics. The tetravalent terbium ion (Tb4+) is non-luminescent and its coexistence with Tb3+ will reduce the green emission of Tb3+.

Properties of terbium compounds

Chalcogenides

Oxides

Terbium has a variety of oxides. The most easily obtained is terbium(III,IV) oxide, which can be produced by the decomposition of terbium compounds such as the hydroxide, the oxalate and the p-aminobenzoate. Terbium(III,IV) oxide, because the oxide contains both trivalent terbium and tetravalent terbium, can be decomposed by reacting with nitric acid to produce terbium(III) nitrate, releasing oxygen in the progress:

2 Tb4O7 + 24 HNO3 → 8 Tb(NO3)3 + 12 H2O + O2↑ It is refluxed in a mixture of acetic acid and hydrochloric acid, which can separate trivalent and tetravalent terbium:

Tb4O7 + 6 HCl → 2 TbO2 + 2 TbCl3 + 3 H2O It reacts with dicyandiamide at a high temperature to obtain Tb2O2CN2. Another common oxide of terbium is terbium(III) oxide, which can be obtained from the reduction of hydrogen from terbium(III,IV) oxide at 1300 °C. A p-type semiconductor is formed after doping with calcium. Terbium(IV) oxide can be prepared by treating terbium(III,IV) oxide with dilute hydrochloric acid, its hydrate TbO2·xH2O can be obtained by oxidizing terbium(III) hydroxide with potassium persulfate in the presence of silver nitrate. Terbium(IV) oxide can form mixed crystals with praseodymium(IV) oxide.

Other chalcogenides Terbium(III) sulfide is one of the sulfides of terbium, which can be obtained by reacting with sulfur in a stoichiometric ratio. It can also be obtained by reacting terbium(III,IV) oxide with carbon disulfide and hydrogen sulfide at high temperature. It reacts with hydrofluoric acid solution to give terbium(III) fluoride hemihydrate. Terbium(III) selenide can be obtained by the reaction of terbium polyselenide TbSe1.9 with metal terbium, which can form black needle-like crystals with U2S3 structure and space group Pnma. Terbium monochalcogenides, TbZ (Z = S, Se or Te), can be prepared by directly reacting terbium with the corresponding chalcogen. These chalcogenides are black and have a NaCl structure. They have metallic conductivity and consist of Ln3+ and Z2- ions with 1 electron from each cation delocalized in a conduction band.

Halides and halogen complexes

Terbium can form four trihalides in the form TbX3 (X=F, Cl, Br, I), which, except the fluoride, are easily soluble in water, and are strong electrolytes in water. They can be prepared by reacting terbium with the corresponding halogen:

2Tb (s) + 3F2 (g) → 2TbF3 (s) [a white substance] 2Tb (s) + 3Cl2 (g) → 2TbCl3 (s) [a white substance] 2Tb (s) + 3Br2 (g) → 2TbBr3 (s) [a white substance] 2Tb (s) + 3I2 (g) → 2TbI3 (s) Anhydrous terbium halides can be prepared by reacting oxides or halides hydrates:

Tb2O3 + 6 NH4Cl → 2 TbCl3 + 3 H2O + 6 NH3↑ TbCl3·6H2O + 6 SOCl2 → TbCl3 + 6 SO2↑ + 12 HCl↑ Terbium(II) halides are obtained by annealing Tb(III) halides in presence of metallic Tb in tantalum containers. Terbium also forms a sesquichloride Tb2Cl3, which can be further reduced to TbCl by annealing at 800 °C. This terbium(I) chloride forms platelets with layered graphite-like structure. Terbium(IV) fluoride is the only halide that tetravalent terbium can form, and has strong oxidizing properties. It is also a strong fluorinating agent, emitting relatively pure atomic fluorine when heated, rather than the mixture of fluoride vapors emitted from cobalt(III) fluoride or cerium(IV) fluoride. It can be obtained by reacting terbium(III) chloride or terbium(III) fluoride with fluorine gas at 320 °C:

2 TbF3 + F2 → 2 TbF4 When TbF4 and CsF is mixed in a stoichiometric ratio, in a fluorine gas atmosphere, CsTbF5 is obtained. It is an orthorhombic crystal, with space group Cmca, with a layered structure composed of [TbF8]4− and 11-coordinated Cs+. The compound BaTbF6 can be prepared in a similar method. It is an orthorhombic crystal, with space group Cmma. The compound [TbF8]4− also exists.

Organoterbium compounds

Organoterbium compounds are a class of organic metal compounds containing Tb-C bonds. The cyclopentadienyl complexes of terbium were studied in the early stage. They can be prepared by the reaction of sodium cyclopentadienide and anhydrous terbium halide in tetrahydrofuran, such as:

TbCl3 + 3 C5H5Na → (C5H5)3Tb + 3 NaCl TbI2 + 2 (C5HiPr4)Na → (C5HiPr4)2Tb + 2 NaI However, this compound has limited usage and academic interest. Like the other lanthanides, metal-carbon σ bonds are found in alkyls of terbium such as [TbMe6]3− and Tb[CH(SiMe3)2]3. The alkyls and aryls can be prepared by metathesis in tetrahydrofuran on ether solutions:

TbCl3 + 3 LiR → TbR3 + 3 LiCl TbCl3 + 4 LiR → Li[TbR4] + 3 LiCl3

Other compounds

Oxoacid salts

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Terbium compounds

Start with the simplest possible case. Write down what Terbium compounds 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 Terbium compounds 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 Terbium compounds 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 Terbium compounds

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

Read the reference excerpt below once, without taking notes.
Close the page and write down what Terbium compounds 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.
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Frequently asked questions

What is Terbium compounds in simple terms?

Terbium compounds are compounds formed by the lanthanide metal terbium (Tb). Terbium generally exhibits the +3 oxidation state in these compounds, such as in TbCl3, Tb(NO3)3 and Tb(CH3COO)3.

Why does Terbium compounds 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 Terbium compounds?

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 Terbium compounds.