For 10 points, name this type of bond in which electrons are shared, contrasted with ionic bonds.
Heitler and London were the first to provide a quantum mechanical explanation of this type of bond, using the bond between the two atoms of molecular hydrogen. Varieties of this type of bond include sigma bonds, the strongest variety, and the weaker pi bonds. Depending on the electronegativity of the atoms involved, this type of bond can be polar or non-polar. For 10 points, name this type of bond in which electrons are shared, contrasted with ionic bonds.
Heitler and London were the first to provide a quantum mechanical explanation of this type of bond, using the bond between the two atoms of molecular hydrogen.
{covalent} bonds