Fundamentals of Chemistry
DOE-HDBK-1015/1-93
CHEMICAL BONDING
Rev. 0
CH-01
Page 33
Combining Elements
The Laws of Definite Proportions and Multiple Proportions and the related portions of atomic
theory form the bases for most quantitative calculations involving chemical reactions. Applying
the basic chemical laws to chemical bonding will help the reader to understand the probability
and proportions involved in chemical reactions. Regardless of the type of bond (ionic, covalent,
coordinate covalent, or metallic), specific amounts of one element will react with specific
amounts of the element(s) with which it is combined.
If two substances are placed together in a container, in any ratio, the result is a mixture. When
a teaspoon of sugar is added to a glass of water, it will slowly dissolve into the water and
disappear from view. As a result, the molecules of sugar are evenly distributed throughout the
water and become mixed with the water molecules. Because the sugar and water mixture is
uniform throughout, it is said to be homogeneous. A homogeneous mixture of two or more
substances is called a solution. The reason solutions are classified as mixtures rather than as
compounds is because the composition is not of fixed proportion.
All solutions consist of a solvent and one or more solutes. The solvent is the material that
dissolves the other substance(s). It is the dissolving medium. In the water-sugar solution, the
water is the solvent. The substances that dissolve in the solution are called solutes. In the
water-sugar solution, sugar is the solute. It is not always easy to identify which is the solvent
and which is the solute (for example, a solution of half water and half alcohol).
Solutions can exist in any of the three states of matter, solid, liquid, or gas. The earth's
atmosphere is a gaseous solution of nitrogen, oxygen, and lesser amounts of other gases. Wine
(water and alcohol) and beer (water, alcohol, and CO ) are examples of liquid solutions. Metal
2
alloys are solid solutions (14-karat gold is gold combined with silver or copper).
One factor that determines the degree and/or rate at which a reaction takes place is solubility.
Solubility is defined as the maximum amount of a substance that can dissolve in a given amount
of solvent at a specific temperature. At this point, the solution is said to be saturated. A
solution is saturated when equilibrium is established between the solute and the solvent at a
particular temperature. Equilibrium is the point at which the rates of the forward and reverse
reactions are exactly equal for a chemical reaction if the conditions of reaction are constant.
Kinetics is the study of the factors which affect the rates of chemical reactions. There are five
principle factors to consider: concentration, temperature, pressure, the nature of the reactants,
and the catalyst.
