rules of valence summation

例句：

1. 1.The rules of valence summation are crucial for understanding the electronic structure of molecules.
   价电子规则对于理解分子的电子结构至关重要。
2. 2. In quantum chemistry, the rules of valence summation are used to describe the behavior of electrons in atoms and molecules.
   在量子化学中，价电子规则用于描述原子和分子中电子的行为。
3. 3. The application of the rules of valence summation has greatly improved our understanding of chemical reactions.
   应用价电子规则极大地提高了我们对化学反应的理解。