It is shown that polar bonds can be as well considered to be resonating between two covalent states as between one covalent state and an ionic state. The limitation on the number ofKelectrons in an isolated hydrogen atom does not prevent a hydrogen atom from being bonded at the same time to two other atoms, provided they are sufficiently electronegative. Likewise, a carbon or nitrogen atom, suitably surrounded by electronegative atoms, can hold more than four (bonding) electropairs in its valence shell. It is suggested that Pauling's ``magnetic criterion for bond type'' does not distinguish between covalent bonds and ``ionic bonds,'' but between covalent bonds of different polarity.
展开▼
