Difference Between VBT and CFT

Key Difference – VBT vs CFT

VBT一词代表价键理论。这是一种用于描述原子之间不同化学键的形成的理论。该理论解释了原子轨道形成化学键的重叠或混合。CFT一词代表晶体场理论。这是一种旨在解释电子轨道（通常是能量的电子壳）（通常是d或f轨道）的破裂（电子壳）的模型，这是由于周围环境产生的静态电场anionor anions (orligands). The key difference between VBT and CFT is thatVBT explains the mixing of orbitals whereas CFT explains the splitting of orbitals.

内容

1.Overview and Key Difference
2.What is VBT
3.什么是CFT
4.Side by Side Comparison – VBT vs CFT in Tabular Form
5.概括

What is VBT

VBT一词代表价键理论。它解释了共价化合物的化学键合。因此，VBT解释了如何covalent bondis formed. A covalent bond is formed via sharing of electrons between atoms. Atoms share electrons to fill their electron configuration (otherwise they are unstable). The electrons are shared by mixing or overlapping ofatomic orbitals。But before overlapping occurs, several requirements should be fulfilled.

共价键有两种类型sigma bonds and pi bonds。这些键是通过原子轨道的重叠形成的。S轨道的重叠总是形成Sigma键。P轨道的重叠会导致PI键的形成。S和P原子轨道的重叠导致形成hybrid orbitals; hence, the process is called hybridization.

There are three major hybrid orbitals that can be formed:

1. sp Hybrid Orbital – Formed via hybridization of one s and one p orbital.
2. sp2 Hybrid Orbital – Formed via hybridization of one s and two p orbitals.
3. sp3 Hybrid Orbital – Formed via hybridization of one s and three p orbitals.

什么是CFT？

CFT一词代表晶体场理论。Crystals field theory is a model designed to explain the breaking of degeneracies (electron shells of equal energy) of electron orbitals (usually d or f orbitals) due to the static electric field produced by a surrounding anion or anions (or ligands). Crystal field theory is often used to demonstrate the behavior oftransition metalions complexes. This theory can also explain about magnetic properties, colors of coordination complexes, hydration enthalpies, etc.

Theory

The interaction between the metal ion and ligands is due to the attraction between the metal ion with a positive charge and the unpaired electrons (negative charge) of the ligand. This theory is mainly based on the changes that occur in five degenerate d electron orbitals (a metal atom has five d orbitals). When a ligand comes close to the metal ion, the unpaired electrons are closer to some d orbitals when compared with other d orbitals of the metal ion. This causes a loss of degeneracy. The electrons in the d orbitals repel the electrons of the ligand (both are negative charged). Hence the d orbitals that are closer to the ligand have a high energy than other d orbitals. This result in the splitting of d orbitals into high energy d orbitals and low energy d orbitals, based on the energy.

影响这种分裂的一些因素包括金属离子的性质，金属离子的氧化态，中央金属离子周围的配体排列以及配体的性质。在基于能量的这些D轨道分裂之后，高能量D轨道之间的差异称为晶体文件分裂参数（∆_oct对于八面体络合物）。

Splitting Pattern

Since there are five d orbitals, the splitting occurs in a ratio of 2:3. In octahedral complexes, two orbitals are in the high energy level (collectively known as eg) and three orbitals are in the lower energy level (collectively known as t2g). In tetrahedral complexes, the opposite occurs; three orbitals are in the higher energy level and two in the lower energy level.

VBT和CFT有什么区别？

VBT与CFT
VBT一词代表价键理论。	CFT一词代表晶体场理论。
Theory
VBT是一种解释通过原子轨道杂交共价键形成的理论。	CFT is a model that is designed to explain the breaking of degeneracies of electron orbitals due to static electric field produced by a surrounding anion or anions
Explanation
VBT explains the mixing of orbitals.	CFT explains the splitting of orbitals.

摘要 - VBT与CFT

VBT一词代表价键理论。CFT一词代表晶体场理论。VBT和CFT之间的主要区别在于，VBT解释了轨道的混合，而CFT解释了轨道的分裂。

Reference:

1. “Crystal field theory.” Wikipedia, Wikimedia Foundation, 18 Feb. 2018,Available here。
2. “Valence Bond Theory.” Chemistry LibreTexts, Libretexts, 24 Jan. 2018,Available here。

Image Courtesy:

1. “Sp hybridization” By Tem5psu – Own work(CC BY-SA 3.0)viaCommons Wikimedia
2. “Octahedral crystal-field splitting” By English Wikipedia user YanA(CC BY-SA 3.0)viaCommons Wikimedia