原子价是化学中最重要的概念之一,但迄今为止仍缺乏严格而又被普遍接受的定义.较为通用的是Pauling所下的1个定义:1个元素的原子价是指它的1个原子和其它原子形成的共价键数.即V_A=∑键级.此定义对只形成正常共价键的分子非常适用.但在蓬勃发展中的金属有机化学、原子簇化学及现代无机化学中却遇到了许多困难.例如在CO分子中,∑键级=3,根据Pauling共价定义则有V_c=V_o=3.这是不能令人接受的,其中关键问题是化 Atomic valence is one of the most important concepts in chemistry, but so far it lacks a strict and universally accepted definition. One of the more generalized definitions of Pauling is that the atomic valence of an element refers to one of its Atoms and other atoms formed by the number of covalent bonds, V_A = Σ key-level This definition is only suitable for the formation of normal covalent bond molecules, but in the flourishing metalorganic chemistry, atomic cluster chemistry and modern inorganic chemistry For example, Σ = 3 in the CO molecule and V_c = V_o = 3 according to the Pauling covalent definition, which is unacceptable and the key problem is to