In chemistry, a cyanide is a chemical compound that contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at 114 °C (237 °F), and boils to a violet gas at 184 °C (363 °F). The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek Ιώδης, meaning 'violet'.
Cyanogen is the chemical compound with the formula (CN)2. The simplest stable carbon nitride, it is a colorless and highly toxic gas with a pungent odor. The molecule is a pseudohalogen. Cyanogen molecules consist of two CN groups – analogous to diatomic halogen molecules, such as Cl2, but far less oxidizing. The two cyano groups are bonded together at their carbon atoms: N≡C‒C≡N, although other isomers have been detected. The name is also used for the CN radical, and hence is used for compounds such as cyanogen bromide (NCBr) (but see also Cyano radical.)
Lead(II) iodide is a chemical compound with the formula PbI
2. At room temperature, it is a bright yellow odorless crystalline solid, that becomes orange and red when heated. It was formerly called plumbous iodide.
In chemistry, an interhalogen compound is a molecule which contains two or more different halogen atoms and no atoms of elements from any other group.
Hydrogen iodide (HI) is a diatomic molecule and hydrogen halide. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a strong acid. Hydrogen iodide and hydroiodic acid are, however, different in that the former is a gas under standard conditions, whereas the other is an aqueous solution of the gas. They are interconvertible. HI is used in organic and inorganic synthesis as one of the primary sources of iodine and as a reducing agent.
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I−) in a crystal lattice. It is used mainly as a nutritional supplement and in organic chemistry. It is produced industrially as the salt formed when acidic iodides react with sodium hydroxide. It is a chaotropic salt.
Lithium iodide, or LiI, is a compound of lithium and iodine. When exposed to air, it becomes yellow in color, due to the oxidation of iodide to iodine. It crystallizes in the NaCl motif. It can participate in various hydrates.
Zinc iodide is the inorganic compound with the formula ZnI2. It exists both in anhydrous form and as a dihydrate. Both are white and readily absorb water from the atmosphere. It has no major application.
Thallium(I) iodide is a chemical compound with the formula TlI. It is unusual in being one of the few water-insoluble metal iodides, along with AgI, CuI, SnI2, SnI4, PbI2 and HgI2.
Iodine compounds are compounds containing the element iodine. Iodine can form compounds using multiple oxidation states. Iodine is quite reactive, but it is much less reactive than the other halogens. For example, while chlorine gas will halogenate carbon monoxide, nitric oxide, and sulfur dioxide, iodine will not do so. Furthermore, iodination of metals tends to result in lower oxidation states than chlorination or bromination; for example, rhenium metal reacts with chlorine to form rhenium hexachloride, but with bromine it forms only rhenium pentabromide and iodine can achieve only rhenium tetraiodide. By the same token, however, since iodine has the lowest ionisation energy among the halogens and is the most easily oxidised of them, it has a more significant cationic chemistry and its higher oxidation states are rather more stable than those of bromine and chlorine, for example in iodine heptafluoride.
A cyanogen halide is a molecule consisting of cyanide and a halogen. Cyanogen halides are chemically classified as pseudohalogens.
The polyiodides are a class of polyhalogen anions composed entirely of iodine atoms. The most common member is the triiodide ion, I−
3. Other known larger polyiodides include [I4]2−, [I5]−, [I6]2−, [I7]−, [I8]2−, [I9]−, [I10]2−, [I10]4−, [I11]3−, [I12]2−, [I13]3−, [I14]4-, [I16]2−, [I22]4−, [I26]3−, [I26]4−, [I28]4− and [I29]3−. All these can be considered as formed from the interaction of the I–, I2, and I−
3 building blocks.
Hypoiodous acid is an inorganic compound with the chemical formula HOI.It forms when an aqueous solution of iodine is treated with mercuric or silver salts. It rapidly decomposes by disproportionation:
Rubidium silver iodide is a ternary inorganic compound with the formula RbAg4I5. Its conductivity involves the movement of silver ions within the crystal lattice. It was discovered while searching for chemicals which had the ionic conductivity properties of alpha-phase silver iodide at temperatures below 146 °C for AgI.
Arsenic triiodide is the inorganic compound with the formula AsI3. It is an orange to dark red solid that readily sublimes. It is a pyramidal molecule that is useful for preparing organoarsenic compounds.
Iron(II) iodide is an inorganic compound with the chemical formula FeI2. It is used as a catalyst in organic reactions.
Iron(III) iodide is an inorganic compound with the chemical formula FeI3. It is a thermodynamically unstable compound that is difficult to prepare. Nevertheless, iron(III) iodide has been synthesised in small quantities in the absence of air and water.
Neodymium(II) iodide or neodymium diiodide is an inorganic salt of iodine and neodymium the formula NdI2. Neodymium uses the +2 oxidation state in the compound.
Astatine compounds are compounds that contain the element astatine (At). As this element is very radioactive, few compounds have been studied. Less reactive than iodine, astatine is the least reactive of the halogens. Its compounds have been synthesized in nano-scale amounts and studied as intensively as possible before their radioactive disintegration. The reactions involved have been typically tested with dilute solutions of astatine mixed with larger amounts of iodine. Acting as a carrier, the iodine ensures there is sufficient material for laboratory techniques to work. Like iodine, astatine has been shown to adopt odd-numbered oxidation states ranging from −1 to +7.
