Bond Polarity

Electronegativity Trend Page 161 in textbook

Electronegativity  A measure of the ability of an atom in a chemical compound to attract electrons.  atom with higher Electronegativity   -  atom with lower Electronegativity   +

Bond Polarity  Most bonds are a blend of ionic and covalent characteristics.

 electrons are shared equally  usually formed by identical atoms Nonpolar Covalent Bond

++ -- Polar Covalent Bond  electrons are shared unequally  results in partial charges (dipole)

zNonpolar zPolar zIonic Bond Polarity Electronegativity Diff. ≤ 0.3 Between 0.3 and 1.7 ≥ 1.7

POLAR MOLECULE  Called “Dipole” – is a molecule with two differently charged ends (+) and (-)  Polar molecules align themselves in an electric field.

Dipole Moment  Direction of the polar bond in a molecule.  Arrow points toward the more electronegative atom. H Cl ++ --

Molecular Polarity  Depends on:  Electronegativity  Molecular shape

z Metallic Bonding z Electrons can move freely because of the overlapping of vacant or partially vacant s,p,d orbital's (sea of electrons). z The ability of the electrons to move about freely accounts for the properties of metals.