帮助学生掌握化学键性能概念——从化学键的键长与键能关系理解C-X键的键长极限

To Learn About the Concept of Chemical Bond Performance——Understanding the Bond Length Limit of C-X from the Relationship Between the Bond Length and Bond Energy

同一类型化学键C-X的键长与键能有良好的线性关系。就键长变化对键能变化的敏感度而言,碳-碳键的键长随键能的变化比碳-氢键迅速,前者是后者的2倍多;碳-卤键的键长随键能的变化是碳-氮/氧键变化的5倍。对有机化合物的碳-碳、碳-氢、碳-氮/氧键及碳-卤键,它们的极限长度分别为174.71、119.52、162.58和277.61pm。应用化学键的极限长度可帮助我们理解有机化合物的反应活性。

There is a good linear relationship between the bond length and the bond energy for a same type of chemical bond C-X. As for the sensitivity of bond length to its bond energy change,the bond length of carbon-carbon bond changes faster with bond energy than that of carbon-hydrogen bond,and the former is over 2 times than that of the latter. The mentioned change of the carbon-halogen bond is 5 times greater than that of the carbon-nitrogen/oxygen bond. For the carbon-carbon,carbon-hydrogen,carbon-nitrogen/oxygen bonds and carbon-halogen bonds of organic compounds,their bond length limits are 174. 71,119. 52,162. 58 and 277. 61 pm respectively. The bond length limit is helpful for us to understand the reactivity of organic compounds.