chemistry

Selenide

Selenide 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 Selenide rather than just read about it. In short: A selenide is a chemical compound containing a selenium with oxidation number of −2. Similar to sulfide, selenides occur both as inorganic compounds and as organic derivatives, which are called organoselenium compound.

Key takeaways

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

Reference excerpt

A selenide is a chemical compound containing a selenium with oxidation number of −2. Similar to sulfide, selenides occur both as inorganic compounds and as organic derivatives, which are called organoselenium compound.

Inorganic selenides

The parent inorganic selenide is hydrogen selenide (H2Se). It is a colorless, malodorous, toxic gas. It dissolves in aqueous solution, to give the hydrogenselenide or biselenide ion HSe−. At higher pH, selenide forms. Solutions of hydrogen selenide and selenide are oxidized by air to give elemental selenium:

2 SeH− + O2 → 2 Se + 2 OH− Most elements form selenides. They sometimes have salt-like properties, e.g. sodium selenide, but most exhibit covalent bonding, e.g. molybdenum diselenide. Their properties are diverse, mirroring the diverse properties of the corresponding sulfides. As indicated by the fact that only a few thousand tons of selenium are produced annually, the subset of selenium compounds called selenides find few applications. Commercially significant is zinc selenide, which is used in some infrared optics. Cadmium selenide is a pigment but its use has been declining because of environmental considerations. Copper indium selenide (CuInSe2) has attractive potential for photovoltaic devices, but these applications have not been implemented widely. Similarly, quantum dots based on metal selenides have been extensively investigated for their distinctive spectral properties. Core-shell alloys of cadmium sulfide and selenide are of interest in imaging and phototherapy. Many selenide minerals are known. Usually selenium partially substitutes for sulfide in many sulfide minerals. The degree of substitution is only of commercial interest for copper sulfide ores, in which case selenium is recovered as a by-product of copper refining. Some selenide minerals include ferroselite and umangite

Organic and biological selenides

Selenides are common in organic chemistry. They have two Se-C bonds, akin to organic sulfides. Examples include dimethyl selenide, selenomethionine, and Se-methylselenocysteine. Such compounds have few applications.

Examples Gallium(II) selenide Indium(III) selenide Lead selenide Copper selenide

Worked examples

Example 1 — a first encounter with Selenide

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

In research: Selenide 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 Selenide 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: Selenide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chalcogenides, Selenides, Selenium(−II) compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Selenide 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 “Selenide” →

Affiliate

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

How to study Selenide in 20 minutes

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

Frequently asked questions

What is Selenide in simple terms?

Why does Selenide 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 Selenide?

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 Selenide.