What are the halogens?

The halogens are the Group 17 elements: fluorine, chlorine, bromine, iodine, and astatine.

Where are halogens usually found in nature?

Because they are reactive, they are usually found combined in compounds, especially as halide ions in seawater, brines, and minerals.

How does halide-ion oxidizability change down the group?

It generally increases down the group: iodide is relatively easy to oxidize, while fluoride is the most difficult.

How is fluorine prepared commercially?

Fluorine is produced by electrolysis of a molten mixture of potassium hydrogen fluoride and anhydrous hydrogen fluoride, with fluorine forming at the anode.

How is commercial bromine produced from brine?

Chlorine oxidizes bromide ions in the brine to liquid bromine, while chlorine is reduced to chloride ions.

Inorganic chemistryLesson 3 of 3 in the course Representative Metals, Metalloids, and Nonmetals

Halogens: Occurrence, Properties, Compounds, Preparation, and Uses

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Halogens are highly reactive elements, so they are not generally found as free elements in nature. Instead, they occur mainly as halide ions in salts and other compounds. This lesson examines where halogens are found and how chemists obtain the elements from their compounds.

The Group 17 elements are fluorine, chlorine, bromine, iodine, and astatine. Their high reactivity means they readily form compounds. Halide ions occur throughout the environment, especially in seawater, where chloride is far more abundant than the other halides. Seawater contains about $0.54\,\text{M}$ chloride ion, while the concentrations of the other halides are below $10^{-4}\,\text{M}$ .

All flashcards

What are the halogens?: The halogens are the Group 17 elements: fluorine, chlorine, bromine, iodine, and astatine.
Where are halogens usually found in nature?: Because they are reactive, they are usually found combined in compounds, especially as halide ions in seawater, brines, and minerals.
How does halide-ion oxidizability change down the group?: It generally increases down the group: iodide is relatively easy to oxidize, while fluoride is the most difficult.
How is fluorine prepared commercially?: Fluorine is produced by electrolysis of a molten mixture of potassium hydrogen fluoride and anhydrous hydrogen fluoride, with fluorine forming at the anode.
How is commercial bromine produced from brine?: Chlorine oxidizes bromide ions in the brine to liquid bromine, while chlorine is reduced to chloride ions.

Quiz questions

Which reagent is commonly used to reduce iodate ions to iodine in commercial iodine preparation?Answer: Sodium hydrogen sulfite
What is iodine's physical state at ordinary conditions?Answer: Grayish-black crystalline solid
Why does iodine dissolve more readily in aqueous iodide solutions than in pure water?Answer: Iodine associates with iodide to form soluble triiodide ions.
What happens when chlorine reacts with cold water?Answer: It disproportionates, forming hypochlorous acid and chloride ions.
What can determine whether tin forms tin(II) chloride or tin(IV) chloride in direct synthesis?Answer: The stoichiometric ratio of tin to chlorine

Based on Chemistry 2e by Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson, PhD (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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