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Commercially, it is usually made by reacting iodine with hydrogen sulfide or hydrazine: [47] 2 I 2 + N 2 H 4 4 HI + N 2. At room temperature, it is a colourless gas, like all of the hydrogen halides except hydrogen fluoride, since hydrogen cannot form strong hydrogen bonds to the large and only mildly electronegative iodine atom. It melts at ...
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.
Commercially, it is usually made by reacting iodine with hydrogen sulfide or hydrazine: [4] 2 I 2 + N 2 H 4 4 HI + N 2. At room temperature, it is a colourless gas, like all of the hydrogen halides except hydrogen fluoride, since hydrogen cannot form strong hydrogen bonds to the large and only mildly electronegative iodine atom. It melts at − ...
At 100 °C, this number decreases to 3.24 due to the increased molecular motion and decreased density, while at 0 °C, the average number of hydrogen bonds increases to 3.69. [42] Another study found a much smaller number of hydrogen bonds: 2.357 at 25 °C. [43] Defining and counting the hydrogen bonds is not straightforward however.
These iodine compounds are hypervalent because the iodine atom formally contains in its valence shell more than the 8 electrons required for the octet rule. 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.
Formula Appearance Use or occurrence Potassium iodide: KI white crystals iodine component of iodized salt Hydrogen iodide: HI colourless gas strong mineral acid Silver iodide: AgI yellow powder that darkens in light photoactive component of silver-based photographic film Thyroxine (3,5,3′,5′-tetraiodothyronine) C 15 H 11 I 4 NO 4: pale ...
The valence is the combining capacity of an atom of a given element, determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in ammonia, nitrogen has a valence of 3; in water, oxygen has a valence of 2; and in hydrogen chloride, chlorine has a valence of 1.
In the molecular orbital model, a common explanation for the hypervalent bonding on the central iodine involves a three-center four-electron bond. The I−I bond is longer than in diatomic iodine, I 2. In ionic compounds, the bond lengths and angles of triiodide vary depending on the nature of the cation. The triiodide anion is easily polarised ...