Bonding

3

These are the skills that are usually tested on the SAT Subject Test in
Chemistry. You should be able to...

Define ionic and covalent bonds, and explain how they form.

Identify the differences in the continuum that exists between

ionic and covalent bonding.

Describe the implications of the type of bond on the structure of

the compound.

Explain the implications of intermolecular forces and van der

Waals forces.

Explain how VSEPR and hybridization solve the need to comply

with known molecular shapes.

This chapter will review and strengthen these skills. Be sure to do the
Practice Exercises at the end of the chapter.

Some elements show no tendency to combine with either like atoms or other

kinds of elements. These elements are said to be monoatomic molecules; three
examples are helium, neon, and argon. A molecule is defined as the smallest
particle of an element or a compound that retains the characteristics of the
original substance. Water is a triatomic molecule since two hydrogen atoms and
one oxygen atom must combine to form the substance water with its characteristic
properties. When atoms do combine to form molecules, there is a shifting of
valence electrons, that is, the electrons in the outer energy level of each atom.
Usually, this results in completion of the outer energy level of each atom. This
more stable form may be achieved by the gain or loss of electrons or the sharing
of pairs of electrons. The resulting attraction of the atoms involved is called a
chemical bond. When a chemical bond forms, energy is released; when this bond
is broken, energy is absorbed.
This relationship of bonding to the valence electrons of atoms can be further
explained by studying the electron structures of the atoms involved. As already
mentioned, the noble gases are monoatomic molecules. The reason can be seen in
the electron distributions of these noble gases as shown in the following table.