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Iodine, the rarest of the nonmetallic halogens, is a metallic looking solid that is moderately reactive, and has a density of 4.933 g/cm 3. It melts at 113.7 °C to a brown liquid and boils at 184.3 °C to a violet-coloured vapour.
The metallic luster of the minerals of the group resembles the luster of the surface of a fresh fracture of metals. It is clearly visible only on the non-oxidized surface of the sample. Minerals that have a metallic luster are, as a result, opaque and heavier than minerals that have a non-metallic luster.
This is an accepted version of this page This is the latest accepted revision, reviewed on 31 December 2024. This article is about the chemical element. For other uses, see Iodine (disambiguation). Chemical element with atomic number 53 (I) Iodine, 53 I Iodine Pronunciation / ˈ aɪ ə d aɪ n, - d ɪ n, - d iː n / (EYE -ə-dyne, -din, -deen) Appearance lustrous metallic gray solid ...
Iodine crystals, showing a metallic lustre. Iodine is a semiconductor in the direction of its planes, with a band gap of ~1.3 eV. It has an electrical conductivity of 1.7 × 10 −8 S•cm −1 at room temperature. [489] This is higher than selenium but lower than boron, the least electrically conducting of the recognised metalloids. [n 51]
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. [1]
The halogens (/ ˈ h æ l ə dʒ ə n, ˈ h eɪ-,-l oʊ-,-ˌ dʒ ɛ n / [1] [2] [3]) are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors [4] would exclude tennessine as its chemistry is unknown and is theoretically expected to ...
There are 40 known isotopes of iodine (53 I) from 108 I to 147 I; all undergo radioactive decay except 127 I, which is stable. Iodine is thus a monoisotopic element.. Its longest-lived radioactive isotope, 129 I, has a half-life of 16.14 million years, which is far too short for it to exist as a primordial nuclide.
Hypervalent iodine oxyanions are known for oxidation states +1, +3, +5, and +7; organic analogues of these moieties are known for each oxidation state except +7. In terms of chemical behavior, λ 3 ‑ and λ 5 ‑iodanes are generally oxidizing and/or electrophilic species. They have been widely applied towards those ends in organic synthesis. [1]