Electronegativity covalent bonds

In the molecules we have described so far, each of the bonds has been a single bond—that is, a covalent bond in which a single pair of electrons is shared by two atoms. But it is possible for atoms to share two or more electron pairs. A double bond is a covalent bond in which two pairs of electrons are shared by two atoms. A triple bond is a covalent bond in which three pairs of electrons are shared by two atoms. As examples, consider ethylene, C2H4, and acetylene, C2H2. Their Lewis formulas are 

Note the octet of electrons on each C atom. Double bonds form primarily with C, N, O, and S atoms. Triple bonds form mostly to C and N atoms. 

You can consider the polar covalent bond as intermediate between a nonpolar covalent bond, as in H2, and an ionic bond, as in NaCl. From this point of view, an ionic bond is simply an extreme example of a polar covalent bond. To illustrate, we can represent the bonding in H2, HCI, and NaCl with electron-dot formulas as follows  

Robert S.Mulliken received the Nobel Prize in chemistry in 1966 for his work on molecular orbital theory (discussed in Chapter 10). 

The bonding pairs of electrons are equally shared in H2, unequally shared in HCI, and essentially not shared in NaCl. Thus, it is possible to arrange different bonds to form a gradual transition from nonpolar covalent to ionic. 

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Electronegativity (Section 2.1) The ability of an atom to attract electrons in a covalent bond. Electronegativity increases across the periodic table from right to left and from bottom to top. 

Polar Covalent Bonding Electronegativity and Dipole Moments... 

This chapter provides a substantial introduction to molecular structure by coupling experimental observation with interpretation through simple classical models. Today, the tools of classical bonding theory—covalent bonds, ionic bonds, polar covalent bonds, electronegativity, Lewis electron dot diagrams, and VSEPR Theory—have all been explained by quantum mechanics. It is a matter of taste whether to present the classical theory first and then gain deeper insight from the... 

Bond energy Ionic bonding Ionic compound Covalent bonding Polar covalent bond Electronegativity Dipole moment... 

Polar Covalent Bonds, Electronegativity, and Bond Dipoles 11... 

Covalent Bonding, Electronegativity, and Bond Polarity (Sections 8.3 and 8.4)... 

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