Final answer:
Place delta notations on a polar covalent bond with δ+ for the less electronegative atom and δ- for the more electronegative atom, based on differences in electronegativity. Represent multiple bonds with the appropriate number of lines in Lewis structures and follow a step-by-step procedure to ensure correct electron distribution according to the octet rule.
Step-by-step explanation:
When determining where to place proper delta notations on covalent bonds, especially in the case of polar covalent bonds, the electronegativity of the atoms involved in the bond must be considered. The atom with the greater electronegativity acquires a partial negative charge (indicated as δ-), while the atom with the lesser electronegativity acquires a partial positive charge (δ+). The delta symbol (δ) indicates that the quantity of charge is less than one. In the Lewis structure of CO2, for example, a double bond is represented by two parallel lines between the carbon atom and each oxygen atom, indicating that two pairs of valence electrons link them.
For more complex molecules, a step-by-step procedure is used to arrange atoms, distribute valence electrons, and form bonds to fulfill the octet rule. This includes arranging a central atom (usually the least electronegative element), determining total valence electrons, placing a bonding pair between adjacent atoms, adding lone pairs to fulfil octets, and forming multiple bonds if necessary to give the central atom an octet.