Fundamental to our understanding of the chemical bond are the
experimentally measured
properties of a bond--its bond length, bond strength, and bond
dipole. From bond
dipole data we will derive the concept of electronegativity--that
some atoms have a greater
power to attract electrons than have others.
These ideas will allow us to discover two types of bonding--ionic and
covalent.
Compounds with large electronegativity differences tend to have unusually
strong bonds. This can be rationalized by proposing that an electron is given
from the more
electropositive atom to the
more electronegative one. This situation creates an anion and a
cation that are bonded
together primarily by electrostatic attraction between the oppositely
charged ions. For bonded
atoms with similar electronegativities, the sharing of electrons between
the nuclei produces a covalent
bonding interaction.