https://doi.org/10.1351/goldbook.B00705
The number of electron-pair @[email protected] between two nuclei in any given @[email protected] For example, in ethene the bond number between the carbon atoms is two, and between the carbon and hydrogen atoms it is one.
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1090 [Terms] [Paper]