The covalent bond theory 1.The H-H covalent bond formation from isolated Hatoms The two hydrogen atoms of different electronic spin come to each other,overlap resulting in 什H2排斥态 a large overlapped area of electronic probability density. 0 HH基态 The system's energy reduces and the hydrogen molecule is formed. 74 pm R The distance between two nuclei(核间距)：R=74pm Essence of covalent bond(共价键的本质)一The atomic orbits overlap to cause increasing electronic probability density which attract the two atomic nuclei. 1.The H-H covalent bond formation from isolated H atoms The two hydrogen atoms of different electronic spin come to each other, overlap resulting in a large overlapped area of electronic probability density. The system’s energy reduces and the hydrogen molecule is formed. The distance between two nuclei (核间距): R0 = 74 pm Essence of covalent bond(共价键的本质)——The atomic orbits overlap to cause increasing electronic probability density which attract the two atomic nuclei. The covalent bond theory