https://doi.org/10.1351/goldbook.B00703
The bonding number \(n\) of a @[email protected] is the sum of the total number of bonding equivalents (@[email protected] bonds) of that @[email protected] to adjacent skeletal atoms in a @[email protected], if any, and the number of attached hydrogen atoms, if any. Examples: SH2: for S, \(n=2\); SH6: for S, \(n=6\).