I.共价鍵的极性和极化性二原子间的共价鍵是由价电子的共有所形成。一个共价單鍵(σ鍵)相当於一堆电子云,它的电荷等於兩个电子的电荷。σ鍵的电子密度,通常是沿联結兩原子的軸而对称分佈着。由兩个相同原子所紐成的分子,如H_2,Cl_2等,鍵內的电子密度不僅沿联結兩原子的軸而对称分佈,同时还按垂直於达軸並通过其中点 I. Polarity and Polarizability of Covalent Bonds The covalent bond between two atoms is formed by the sharing of valence electrons. A single covalent bond (σ bond) is equivalent to a bunch of electron clouds whose charge equals the charge of two electrons. The σ bond electron density is usually symmetrically distributed along the axis connecting the two atoms. New molecules formed by two identical atoms, such as H 2, Cl 2, etc. The electron density in the bond is not only symmetrically distributed along the axis connecting the two atoms, but also perpendicular to the axis and passing through its midpoint