Covalence

and chlorine ions become chloride. Use parentheses if necessary to clear up the number of atoms in the molecule.

COVALENCE

Covalent bonding, as you know, happens between nonmetals and involves the overlapping of orbitals rather than the complete transfer of electrons and the electrostatic attraction between two ions. The shared electrons will occupy the valence orbitals of both atoms at the same time, creating a strong bond, called the covalent bond. This gives each atom an effective octet.

Lattice structures do not occur with covalent bonding. There are many more covalently bonded substances when compared to ionic substances. In H2 for example, there is one electron in each 1s orbital and, when this is shared, they both have an essentially full 1s orbital.

There can be polyatomic molecules that have both covalent and ionic bonding. For situations like sodium nitrate or NaNO3, there is a covalent bonding between the nitrogen and oxygen molecules; however, there is a charge left over, which is a -1 charge. This then makes an ionic bond with sodium, which has a +1 charge.

The Lewis structure is one way to identify covalent bonding, which is based on the eight valence electrons around most of the atoms that are involved in this type of bonding (except for hydrogen, which follows the duet rule). In drawing a Lewis structure, you need to first look at the number of valence electrons around the atom on the periodic table. You then place these electrons as dots around the larger molecule. When they are bonded with another molecule and sharing part of their electrons in an orbital, you draw a line connecting the two atoms. Figure 23 shows what the Lewis Structure looks like:

Figure 23.

Sometimes, this will lead to one line between the atomic structures with single bonds. Two lines can be drawn with a “double bond” and three lines can be drawn with triple bonds. Figure 24 describes three Lewis structures for water, diatomic oxygen, and diatomic nitrogen:

Figure 24.