Just as a language has an alphabet from which words are built, chemistry has an alphabet from which matter is described. However, the chemical alphabet is larger than the one we use for spelling. You may have already figured out that the chemical alphabet consists of the chemical elements. Their role is central to chemistry, for they combine to form the millions and millions of known compounds.
- 2.1: The Elements
- All matter is composed of elements. Chemical elements are represented by a one- or two-letter symbol.
- 2.2: Atomic Theory
- Atoms are the ultimate building blocks of all matter. The modern atomic theory establishes the concepts of atoms and how they compose matter.
- 2.3: The Structure of Atoms
- Atoms are composed of three main subatomic particles: protons, neutrons, and electrons. Protons and neutrons are grouped together in the nucleus of an atom, while electrons orbit about the nucleus.
- 2.4: Nuclei of Atoms
- Elements can be identified by their atomic number and mass number. Isotopes are atoms of the same element that have different masses.
- 2.5: Atomic Masses
- Atoms have a mass that is based largely on the number of protons and neutrons in their nucleus.
- 2.6: Arrangements of Electrons
- Electrons are organized into shells and subshells about the nucleus of an atom.
- 2.7: The Periodic Table
- The chemical elements are arranged in a chart called the periodic table. Some characteristics of the elements are related to their position on the periodic table.
- 2.S: Elements, Atoms, and the Periodic Table (Summary)
- To ensure that you understand the material in this chapter, you should review the meanings of the following bold terms and ask yourself how they relate to the topics in the chapter.
Thumbnail: Ionization energies superimposed on a periodic table. (CC BY-NC-SA; anonymous by request).