chemistry

Sodium periodate

Sodium periodate 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 Sodium periodate rather than just read about it. In short: Sodium periodate is an inorganic salt, composed of a sodium cation and the periodate anion. It may also be regarded as the sodium salt of periodic acid.

Key takeaways

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

Reference excerpt

Sodium periodate is an inorganic salt, composed of a sodium cation and the periodate anion. It may also be regarded as the sodium salt of periodic acid. Like many periodates, it can exist in two different forms: sodium metaperiodate (formula‍ NaIO4) and sodium orthoperiodate (normally Na2H3IO6, but sometimes the fully reacted salt Na5IO6). Both salts are useful oxidising agents.

Preparation Classically, periodate was produced in the form of sodium hydrogen periodate (Na3H2IO6). This commercially available, but can also be produced by the oxidation of iodates with chlorine and sodium hydroxide. Or, similarly, from iodides by oxidation with bromine and sodium hydroxide:

NaIO3 + Cl2 + 4 NaOH → Na3H2IO6 + 2NaCl + H2O NaI + 4 Br2 + 10 NaOH → Na3H2IO6 + 8 NaBr + 4 H2O Modern industrial scale production involves the electrochemical oxidation of iodates, on a lead dioxide (PbO2) anode, with the following standard electrode potential:

H5IO6 + H+ + 2e− → IO−3 + 3 H2O E° = 1.6 V Sodium metaperiodate can be prepared by the dehydration of sodium hydrogen periodate with a strong mineral acid, such as nitric acid:

Na3H2IO6 + 2 HNO3 → NaIO4 + 2 NaNO3 + 2 H2O

Structure Sodium metaperiodate (NaIO4) forms tetragonal crystals (space group I41/a) consisting of slightly distorted IO−4 ions with average I–O bond distances of 1.775 Å; the Na+ ions are surrounded by 8 oxygen atoms at distances of 2.54 and 2.60 Å. Sodium hydrogen periodate (Na2H3IO6) forms orthorhombic crystals (space group Pnnm). Iodine and sodium atoms are both surrounded by an octahedral arrangement of 6 oxygen atoms; however the NaO6 octahedron is strongly distorted. IO6 and NaO6 groups are linked via common vertices and edges. Powder diffraction indicates that Na5IO6 crystallises in the monoclinic system (space group C2/m).

Uses

Sodium periodate can be used in solution to open saccharide rings between vicinal diols leaving two aldehyde groups. This process is often used in labeling saccharides with fluorescent molecules or other tags such as biotin. Because the process requires vicinal diols, periodate oxidation is often used to selectively label the 3′-ends of RNA (ribose has vicinal diols) instead of DNA as deoxyribose does not have vicinal diols. NaIO4 is used in organic chemistry to cleave diols to produce two aldehydes.

In 2013 the US Army announced that it would replace environmentally harmful chemicals barium nitrate and potassium perchlorate with sodium metaperiodate for use in their tracer ammunition.

See also lead tetraacetate - also effective for diol cleavage via the Criegee oxidation

References

See Fatiadi, Synthesis (1974) 229–272 for a review of periodate chemistry.

Illustrations

Worked examples

Example 1 — a first encounter with Sodium periodate

Start with the simplest possible case. Write down what Sodium periodate 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 Sodium periodate 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 Sodium periodate 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 Sodium periodate

In research: Sodium periodate 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 Sodium periodate 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: Sodium periodate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Oxidizing agents, Periodates, Sodium compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Sodium periodate 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 Sodium periodate in 20 minutes

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

Frequently asked questions

What is Sodium periodate in simple terms?

Sodium periodate is an inorganic salt, composed of a sodium cation and the periodate anion. It may also be regarded as the sodium salt of periodic acid.

Why does Sodium periodate 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 Sodium periodate?

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 Sodium periodate.