Abstract
Melting point and bond length are employed to compare cohesive energy relations for metals, tetrahedral semiconductors, and carbides and nitrides that have the rocksalt structure. Cohesion largely is due to electron transfer in each case. However, the values for each of the three series deviate from a simple exchange relation in a different way. The deviation can be associated with semicovalent bonding in metals, electron spin‐pair bond delocalization in the semiconductors, and isolated C or N atoms in octahedral sites effecting an increase in the energy between first and second subset metal d states in the carbides and nitrides.