Summary

Hopefully, the course on college chemistry you have just studied has provided a way for you who have been pursuing an interest in chemistry or who have possibly already been struggling with chemistry to understand this discipline in a much clearer way. As you have seen, chemistry is a wide-reaching subject, ranging from “physical chemistry” or the study of atoms, molecules, chemical reactions, and the properties of solids, liquids, and gases, to things like “organic chemistry” and “biochemistry” that deal with the topic of the chemistry specific to carbon-based molecules, which are the molecules of living things.

As you have hopefully determined in studying this course, the majority of chemistry is about the physical properties of atoms and molecules in singular form as well as the physical properties of molecules in different states, including the molecular properties of gases, solids, and liquids. Most atoms and molecules are not inert and interact with one another in specific chemical and physical ways. This has been the major focus in this course as we learned about how different substances exist in natural and experimental situations.

Chapter one in the course introduced chemistry in its most basic form by covering atoms and their nature. Everything in the universe is made from different types of atoms. As it turns out, atoms have specific sub-particles that make up the basic structure of the atom. There are also numerous different atoms in nature, as we talked about when introducing the periodic table, which outlined the relationships between different types of atoms. Finally, there was a discussion on the concept of the “mole” as it exists in understanding quantities of atoms and molecules.

The focus of chapter two was the structure of atoms. As you have seen, there are specific rules that define how subatomic structures are organized. This chapter looked at the arrangement of electrons, and both the Pauli principle and Aufbau Principle, which define electron relationships inside the atom. Electrons have a natural affinity for the

proton they surround but also allow for affinity of different types of atoms in the formation of larger molecules. This concept was also covered in the chapter.

The main topics of chapter three in the course were the properties of gases. There are specific laws that describe the behavior of gases in chemistry, which were introduced and discussed in this chapter. The study of gases involves the relationship between volume and pressure in a gas and, in the situation of mixed gases, a relationship between the different gases in a given volume. The behavior of gases in relation to the ideal gas law was covered in this chapter as well as the study of the kinetics of gas molecules in a gaseous solution.

Chapter four talked about chemistry as it relates to heat, also called “thermochemistry”. There is an intricate connection between molecules and the temperature of the atoms in the molecules. Concepts of heat capacity and calorimetry were discussed as they relate to a specific molecule. The enthalpy or the total heat in a given system was discussed as it relates to the energy of the system. As in all of physical chemistry, there are specific rules related to the properties of substances at different temperatures, which were also covered in this chapter.

Chapter five in the course got into the subject of chemical bonding and molecular structure. Unless an atom is completely inert, it will have the natural tendency to interact with other atoms. This is certainly the case with ionic substances in chemistry. The chapter looked at the issue of covalence and covalent bonding between molecules and how this should look from an atomic perspective. Because of the different properties of atoms, they exist within molecules in specific three-dimensional arrangements, which was covered in this chapter. The topic of bonding in metallic atoms was also covered as part of this chapter.

Chapter six focused on the inevitability of chemical reactions and on what chemical formulas look like. Molecules and atomic substances tend not to stay separate from one another when put together in the same physical space and reactions will follow a specific pattern. The rates of different reactions and why they occur or do not occur were discussed as well as the issue of the energy of activation necessary to take a group of molecules in one form and turn them into molecules of a different form. Exactly what

happens in chemical reactions was covered as part of this chapter, including the fact that reactions ultimately have an equilibrium state.

The focus of chapter seven in the course was the behavior of solids and liquids. Molecules can exist in crystalline form, depending on the physical circumstances. There are certain molecular forces in play when substances are in crystalline form, which was covered in this chapter. In the same way, liquids have certain properties unique to that state that depend on the atomic nature of the molecule and on the temperature of the liquid. The different forces in play when substances are in liquid form were also discussed in the chapter.

The study of liquids continued in chapter eight with a discussion of solutions and colloids. Solutions involve the dissolution of a substance in a liquid medium. Exactly how this is successfully done was covered as part of this chapter as well as what it means to indicate the “concentration” of a solute in solution. A solution, as you have discovered, is a unique medium for reactions to take place, as it exhibits certain properties that keep things in a given solution and that help drive reactions within the solution. Colloids have certain properties that were also discussed.

Two significant types of reactions were covered in chapter nine in the course—that being oxidation and reduction reactions, which are opposing but interrelated chemical reactions. Because these reactions happen in a balanced way, they are often discussed together. Taken together, an oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion is altered by gaining or losing an electron. You hopefully have come to understand why these reactions are related and how to balance them.

The specific properties of acids and bases were discussed in chapter ten in the course. Methods involved in the titration of acids and bases were discussed as part of this chapter as were properties of strong and weak acids and bases. Buffers, as you have learned, are weak acids or weak bases that prevent significant changes in the pH of a solution; how these substances work in acid-base chemistry was covered. Finally, the topic of hydrolysis was an important part of the discussion in this section.

The focus of chapter eleven in the course was electrochemistry, or the study of electricity as it applies to chemical reactions. Faraday’s law, which states that the amount of substance produced at an electrode is directly proportional to the quantity of charge flowing through an electrochemical cell, was discussed. As you have learned, the basics of electricity in chemical reactions are important to understand because electricity plays a role in many chemical interactions. The different properties of electrical cells and what makes them up was a part of this chapter’s discussion.

While the subjects of organic chemistry and biochemistry are courses of their own, they were instead covered together in chapter twelve because they are important aspects of the study of chemistry. Organic chemistry is carbon-based chemistry and involves a variety of different types of molecules and reactions typically seen in living things. The nature of organic molecules was discussed as well as the functional groups that shape organic molecules and their behavior. Finally, biochemistry and its principles were covered as these types of molecules, too, follow the basic chemical principles already laid out in this course.