Molecules are composed of atoms that are attached together and behave as a unit (Fig. Atoms are extremely tiny to make a line 1 inch long, you would need 217 million iron atoms! Similarly, the smallest part of a compound that maintains the identity of that compound is called a molecule. The smallest part of an element that maintains the identity of that element is called an atom. In contrast, scientists have identified tens of millions of different compounds to date. Today, there are about 118 elements in the known universe which are organized on a fundamental chart called the Periodic Table of Elements (Fig. Water is a compound composed of the elements hydrogen and oxygen. A substance that can be broken down into chemically simpler components (because it has more than one element) is a compound. Aluminum, which is used in soda cans, is an element. A substance that cannot be broken down into chemically simpler components is an element. Elements and CompoundsĪny sample of matter that has the same physical and chemical properties throughout the sample is called a substance. An example of a chemical property is flammability-a materials ability to burn-because burning (also known as combustion) changes the chemical composition of a material. Chemical properties are characteristics that describe how the chemical structure of matter changes during a chemical reaction. Physical Changes, such as melting a solid into a liquid, do not alter the chemical structure of that matter. Physical properties are characteristics that describes matter, such as boiling point, melting point and color. The properties that chemists use to describe matter fall into two general categories. One way chemists describe matter is to assign different kinds of properties to different categories. Part of understanding matter is being able to describe it. Chemistry lies more or less in the middle, which emphasizes its importance to many branches of science. Figure 2.1 shows how many of the individual fields of science are related.įigure 2.1: The Relationships Between Some of the Major Branches of Science. Similarly, geology and chemistry overlap in the field called geochemistry. For example, some biologists and chemists work in both fields so much that their work is called biochemistry. Mathematics and Physics are the languages of science, and we will use them to communicate some of the ideas of chemistry.Īlthough we divide science into different fields, there is much overlap among them. Thus, chemistry is the study of matter, biology is the study of living things, and geology is the study of rocks and the earth. Because the physical universe is so vast, there are many different branches of science (Figure 2.1).

is the process by which we learn about the natural universe by observing, testing, and then generating models that explain our observations. Science is the process by which we learn about the natural universe by observing, testing, and then generating models that explain our observations. This includes advances in medicine, communication, transportation, building infrastructure, food science and agriculture, and nearly every other technical field that you can imagine.Ĭhemistry is one branch of science. From the color that makes a rose so red to the gasoline that fills our cars and the silicon chips that power our computers and cell phones…Chemistry is everywhere! Understanding how chemical molecules form and interact to create complex structures enables us to harness the power of chemistry and use it, just like a toolbox, to create many of the modern advances that we see today. Section 2.1: Chemistry and Matter What is Chemistry?Įverything around us is made up of chemicals. Chapter 2: Atoms and the Periodic Table Section 2.1: Chemistry and Matter What is Chemistry? Physical and Chemical Properties Elements and Compounds Mixtures States of Matter Reactions in Chemistry Section 2.2: How Scientists Study Chemistry The Scientific Method 2.3 Atomic Theory with Historical Perspectives 2.4 Introduction to Elements and the Periodic Table 2.5 Dmitri Mendeleev and the development of the periodic table 2.6 Families of the Periodic Table 2.7 Defining the Atom Basic Atomic Structure – electrons, neutrons, and protons 2.8 Atomic Number – Protons Determine the Identity of an Element 2.9 Atomic Mass, Isotopes, and Molar Mass 2.10 Periodic Table Trends Atomic Size Electronegativity Ionization Energy Metallic and Nonmetallic Character 2.11 Chapter Summary and Homework 2.12 References

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