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A halogen bond is almost collinear with the halogen atom's other, conventional bond, but the geometry of the electron-charge donor may be much more complex.. Multi-electron donors such as ethers and amines prefer halogen bonds collinear with the lone pair and donor nucleus.
The term bond-dissociation energy is similar to the related notion of bond-dissociation enthalpy (or bond enthalpy), which is sometimes used interchangeably.However, some authors make the distinction that the bond-dissociation energy (D 0) refers to the enthalpy change at 0 K, while the term bond-dissociation enthalpy is used for the enthalpy change at 298 K (unambiguously denoted DH° 298).
It is sometimes called the mean bond, bond enthalpy, average bond enthalpy, or bond strength. [ 1 ] [ 2 ] [ 3 ] IUPAC defines bond energy as the average value of the gas-phase bond-dissociation energy (usually at a temperature of 298.15 K) for all bonds of the same type within the same chemical species.
The Born–Haber cycle is an approach to analyze reaction energies.It was named after two German scientists, Max Born and Fritz Haber, who developed it in 1919. [1] [2] [3] It was also independently formulated by Kasimir Fajans [4] and published concurrently in the same journal. [1]
Bond cleavage is also possible by a process called heterolysis. The energy involved in this process is called bond dissociation energy (BDE). [ 2 ] BDE is defined as the " enthalpy (per mole ) required to break a given bond of some specific molecular entity by homolysis," symbolized as D . [ 3 ]
The halogens, being strongly nonmetallic, prefer to form anions rather than cations in aqueous solution. [57] Anion solvation is complicated because the water molecules point the other way: cations bind to the oxygen atom of water, with the hydrogens facing away, while anions prefer to bond asymmetrically to only one of the hydrogen atoms in a ...
As determined by the enthalpies below the corresponding molecules, the enthalpy of reaction for 2-methyl-1-butene going to 2-methyl-butane is −29.07 kcal/mol, which is in great agreement with the value calculated from NIST, [15] −28.31 kcal/mol. For 2-butanone going to 2-butanol, enthalpy of reaction is −13.75 kcal/mol, which again is in ...
The group of halogens is the only periodic table group that contains elements in three of the main states of matter at standard temperature and pressure, though not far above room temperature the same becomes true of groups 1 and 15, assuming white phosphorus is taken as the standard state. [n 1] All of the halogens form acids when bonded to ...