chemistry

Metaborate

Metaborate 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 Metaborate rather than just read about it. In short: A metaborate is a borate anion consisting of boron and oxygen, with empirical formula BO−2. Metaborate also refers to any salt or ester of such anion (e.g. salts such as sodium metaborate NaBO2 or calcium metaborate Ca(BO2)2, and esters such as methyl metaborate CH3BO2).

Key takeaways

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

Reference excerpt

A metaborate is a borate anion consisting of boron and oxygen, with empirical formula BO−2. Metaborate also refers to any salt or ester of such anion (e.g. salts such as sodium metaborate NaBO2 or calcium metaborate Ca(BO2)2, and esters such as methyl metaborate CH3BO2). Metaborate is one of the boron's oxyanions. Metaborates can be monomeric, oligomeric or polymeric. In aqueous solutions metaborate anion hydrolyzes to tetrahydroxyborate [B(OH)4]−. For this reason, solutions or hydrated salts of the latter are often improperly named "metaborates".

Structure

Solid state In the solid state of their salts, metaborate ions are often oligomeric or polymeric, conceptually resulting from the fusion of two or more BO−2 through shared oxygen atoms. In these anions, the boron atom forms covalent bonds with either three or four oxygen atoms. Some of the structures are:

A trimer with formula B3O3−6 or (−B(−O−)−O−)3, consisting of a six-membered ring of alternating boron and oxygen atoms with one extra oxygen atom attached to each boron atom. This form is found, for example, in some anhydrous alkali metal salts like sodium metaborate or potassium metaborate, in α- and β-barium metaborate Ba3(B3O6)2, and in the mixed salt potassium cadmium metaborate KCdB3O6. The three B–O distances are nearly equal in the potassium salt (133.1, 139.8, and 139.8 pm) but significantly different in the sodium one (128.0, 143.3, and 143.3 pm). A polymer of BO−2 units connected by single shared-oxygen bridges; that is, ···(−B(−O−)−O−)n···. Occurs in calcium metaborate CaB2O4 or Ca(BO2)2. A tridimensional network of BO4 tetrahedral groups, as in "zinc metaborate", which is actually a mixed salt zinc metaborate oxide, with the formula (Zn2+)4(O2−)(BO−2)6. A tridimensional regular array of [B(−O−)4]− tetrahedra sharing oxygen vertices, as in the high-pressure and high-temperature γ form of lithium metaborate LiBO2.

Aqueous solution The cyclic trimer anions dissociate almost completely in aqueous solution giving mainly tetrahydroxyborate anions:

B3O3−6 + 6 H2O ↽ − ⇀ {\displaystyle {\ce {<=>>}}} 3 [B(OH)4]− Other molecules and anions, such as B(OH)3, [B3O3(OH)4]−, [B3O3(OH)5]2−, and B4O5(OH)2−4 are less than 5% at 26 °C. In 1937, Nielsen and Ward claimed that the metaborate anion in solution has a linear symmetric structure −O−B+−O− with negative charges on the oxygens and a positive charge on the boron, or O=B−=O with negative charge on the boron. However, this claim has been disproved.

Gas phase The vapor of cesium metaborate has neutral monomers CsBO2 and dimers Cs2[B2O4] as well as ionized versions thereof. The same situation holds for thallium metaborate TlBO2.

Solid solutions In 1964 Hisatsune and Surez investigated the infrared spectrum of metaborate anions in dilute solid solutions of potassium salt in alkali halides such as potassium chloride KCl.

References

Illustrations

Worked examples

Example 1 — a first encounter with Metaborate

Start with the simplest possible case. Write down what Metaborate 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 Metaborate 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 Metaborate 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 Metaborate

In research: Metaborate 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 Metaborate 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: Metaborate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Borate minerals, Borates, Boron oxyanions, so understanding it makes those chapters shorter.
In everyday life: Look for Metaborate 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 Metaborate in 20 minutes

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

Frequently asked questions

What is Metaborate in simple terms?

Why does Metaborate 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 Metaborate?

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 Metaborate.