Electronegativity and Covalent Bonds

What is the role of electronegativity in the distribution of charge within a covalent bond?

Elements which have high electronegativity (top, right corner of the periodic table - aka Mighty Mouse) will ``pull'' charge towards them creating a more negative charge towards their end:

Figure 30.10: $e^{-}$ charge distribution in HF.

Note, the plus sign has an extended arrow-tipped lines. These indicate the dipole moment of the molecule and show the concentration of positive charge (+) and negative charge (arrow-head).

Figure 30.11: $e^{-}$ charge distribution in H$_{2}$O.

What is the name of a bond (molecule) which exhibits a dipole moment?

Polar bond (molecules).