chemistry

Radium compounds

Radium 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 Radium compounds rather than just read about it. In short: Radium compounds are compounds containing the element radium (Ra). Due to radium's radioactivity, not many compounds have been well characterized.

Key takeaways

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

Reference excerpt

Radium compounds are compounds containing the element radium (Ra). Due to radium's radioactivity, not many compounds have been well characterized. Solid radium compounds are white as radium ions provide no specific coloring, but they gradually turn yellow and then dark over time due to self-radiolysis from radium's alpha decay. Insoluble radium compounds coprecipitate with all barium, most strontium, and most lead compounds.

Oxides and hydroxides Radium oxide (RaO) has not been characterized well past its existence, despite oxides being common compounds for the other alkaline earth metals. Radium hydroxide (Ra(OH)2) is the most readily soluble among the alkaline earth hydroxides and is a stronger base than its barium congener, barium hydroxide. It is also more soluble than actinium hydroxide and thorium hydroxide: these three adjacent hydroxides may be separated by precipitating them with ammonia.

Halides Radium fluoride (RaF2) is a highly radioactive compound. It can be coprecipitated with lanthanide fluorides. Radium fluoride has the same crystal form as calcium fluoride (fluorite). It can be prepared by the reaction of radium metal and hydrogen fluoride gas:

Ra + 2 HF → RaF2 + H2 Radium chloride (RaCl2) is a colorless, luminous compound. It becomes yellow after some time due to self-damage by the alpha radiation given off by radium when it decays. Small amounts of barium impurities give the compound a rose color. It is soluble in water, though less so than barium chloride, and its solubility decreases with increasing concentration of hydrochloric acid. Crystallization from aqueous solution gives the dihydrate RaCl2·2H2O, isomorphous with its barium analog. Radium bromide (RaBr2) is also a colorless, luminous compound. In water, it is more soluble than radium chloride. Like radium chloride, crystallization from aqueous solution gives the dihydrate RaBr2·2H2O, isomorphous with its barium analog. The ionizing radiation emitted by radium bromide excites nitrogen molecules in the air, making it glow. The alpha particles emitted by radium quickly gain two electrons to become neutral helium, which builds up inside and weakens radium bromide crystals. This effect sometimes causes the crystals to break or even explode.

Other compounds Radium nitrate (Ra(NO3)2) is a white compound that can be made by dissolving radium carbonate in nitric acid. As the concentration of nitric acid increases, the solubility of radium nitrate decreases, an important property for the chemical purification of radium. Radium forms much the same insoluble salts as its lighter congener barium: it forms the insoluble sulfate (RaSO4, the most insoluble known sulfate), chromate (RaCrO4), carbonate (RaCO3), iodate (Ra(IO3)2), tetrafluoroberyllate (RaBeF4), and nitrate (Ra(NO3)2). With the exception of the carbonate, all of these are less soluble in water than the corresponding barium salts, but they are all isostructural to their barium counterparts. Additionally, radium phosphate, radium oxalate, and radium sulfite are probably also insoluble, as they coprecipitate with the corresponding insoluble barium salts. The great insolubility of radium sulfate (at 20 °C, only 2.1 mg will dissolve in 1 kg of water) means that it is one of the less biologically dangerous radium compounds. The large ionic radius of Ra2+ (148 pm) results in weak complexation and poor extraction of radium from aqueous solutions when not at high pH.

See also Category:Radium compounds Francium compounds Actinium compounds Barium compounds

References

Worked examples

Example 1 — a first encounter with Radium compounds

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

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

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Radium compounds” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Radium compounds in 20 minutes

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

Frequently asked questions

What is Radium compounds in simple terms?

Radium compounds are compounds containing the element radium (Ra). Due to radium's radioactivity, not many compounds have been well characterized.

Why does Radium 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 Radium 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 Radium compounds.