Difference Between Homolytic and Heterolytic Bond Dissociation Energy

Key Difference – Homolytic vs Heterolytic Bond Dissociation Energy

Bond dissociation energy is a measure of the strength of a chemical bond. A bond can be dissociated in a homolytic manner or a heterolytic manner. Bond dissociation energy is defined as the standardenthalpychange when a chemical bond is cleaved via homolysis. Homolytic bond dissociation energy is the amount of energy required to dissociate a chemical bond via他molysiswhereas heterolytic bond dissociation energy is the amount of energy required to clave a chemical bond via heterolysis.同一化合物的均质键解离能的值不同于杂键键解离能的值。This is the key difference between homolytic and heterolytic bond dissociation energy.

内容

1.Overview and Key Difference
2.What is Homolytic Bond Dissociation Energy
3.什么是杂键解离能
4.Side by Side Comparison – Homolytic vs Heterolytic Bond Dissociation Energy in Tabular Form
5.概括

What is Homolytic Bond Dissociation Energy?

均质键解离能是通过溶血解离化学键所需的能量。Hemolysis of a chemical bond is the symmetric cleavage of the bond forming tworadicals, not two ions. Here, the bond electrons between the atoms are divided into two halves and are taken by the two atoms. For example, the homolytic cleavage of aSigma Bond形成两个具有每个自由基一个未配对电子的自由基。

The bond dissociation energy is defined as the amount of energy required to cleave a chemical bond via hemolysis at standard conditions. The homolytic bond dissociation energy determines whether a chemical bond is strong or weak. If the value of homolytic bond dissociation energy is higher, it indicates that a high amount of energy should be provided in order to cleave that bond; hence, it is a strong bond.

什么是杂键解离能?

Heterolytic bond dissociation energy is the amount of energy required to clave a chemical bond via heterolysis. Heterolysis is the cleavage of a chemical bond in asymmetric manner. Heterolysis formscations and anions. This is because, in heterolysis, the bond electron pair is taken by the electronegative atom (it is converted into the anion) whereas the other atom takes no electrons (it forms the cation).

与分子的均匀分解相比，同一分子的杂解与同溶解的值不同。这意味着化合物的均其键解离能与同一分子的杂键解离能不同。

Ex: Let us consider the cleavage of the H-H bond in the hydrogen molecule.

Homolytic bond dissociation: H₂→H● + H●（键解离能为104 kcal/mol）

杂键解离：H₂→ H⁺+ H^–(bond dissociation energy is 66 kcal/mol)

均质和杂键解离能之间有什么区别？

均利性与杂化键解离能
均质键解离能是通过溶血解离化学键所需的能量。	Heterolytic bond dissociation energy is the amount of energy required to clave a chemical bond via heterolysis.
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Homolytic bond dissociation energy is associated with the formation of radicals by the cleavage of chemical bonds.	Heterolytic bond dissociation energy is associated with the formation of cations and anions by the cleavage of chemical bonds.

概括– Homolytic vs Heterolytic Bond Dissociation Energy

键解离能是在标准条件下通过均匀分解化学键所需的能量。键切割有两种类型，作为同型和杂化。均质键裂解形成自由基，而杂键裂解形成阳离子和阴离子。均质和杂键解离能之间的关键差异在于，均取代键解离能的值与同一化合物的杂键键解离能的值不同。

Reference:

1.“键 - 分解能”。Wikipedia，Wikimedia基金会，2018年2月28日，Available here.
2. “Heterolysis (Chemistry).” Wikipedia, Wikimedia Foundation, 19 Feb. 2018,Available here.
3. “Bond Dissociation Energies = Homolytic Cleavage.” Master Organic Chemistry RSS,Available here.

Image Courtesy:

1. “Homolysis (Chemistry)” By Jürgen Martens – Jürgen Martens (Public Domain) viaCommons Wikimedia
2. “Heterolysis (Chemistry)” By [Jürgen Martens – Jürgen Martens(CC BY-SA 3.0)viaCommons Wikimedia