2: Elements, Atoms, and the Periodic Table
- Page ID
- 469196
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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.
- 2.0: Prelude to Elements, Atoms, and the Periodic Table
- The hardest material in the human body is tooth enamel. It has to be hard so that our teeth can serve us for a lifetime of biting and chewing; however, tough as it is, tooth enamel is susceptible to chemical attack. Acids found in some foods or made by bacteria that feed on food residues on our teeth are capable of dissolving enamel. Unprotected by enamel, a tooth will start to decay, thus developing cavities and other dental problems.
- 2.1: Chemical Elements and Symbols
- An element is a substance that cannot be broken down into simpler chemical substances. There are about 90 naturally occurring elements known on Earth. Using technology, scientists have been able to create nearly 30 additional elements that do not occur in nature. Today, chemistry recognizes 118 elements—some of which were created an atom at a time.
- 2.2: 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.
- 2.3: 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.
- 2.4: 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.
- 2.5: 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.
- 2.6: Atomic Masses
- Atoms have a mass that is based largely on the number of protons and neutrons in their nucleus.
- 2.7: Electronic Structure of Atoms
- Electrons in atoms have quantized energies. The state of electrons in atoms is described by four quantum numbers. Electrons are organized into shells and subshells about the nucleus of an atom.
- 2.8: Electron Configurations
- There are a set of general rules that are used to figure out the electron configuration of an atomic species: Aufbau Principle, Hund's Rule and the Pauli-Exclusion Principle.
- 2.9: Electron Configurations and the Periodic Table
- The arrangement of electrons in atoms is responsible for the shape of the periodic table. Electron configurations can be predicted by the position of an atom on the periodic table
- 2.10: Periodic Trends
- 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.
- 2.11: Electron-Dot Symbols
- A Lewis electron dot diagram (or electron dot diagram or a Lewis diagram or a Lewis structure) is a representation of the valence electrons of an atom that uses dots around the symbol of the element.
- 2.E: Elements, Atoms, and the Periodic Table (Exercises)
- These are homework exercises to accompany Chapter 2 of the Ball et al. "The Basics of GOB Chemistry" Textmap.
- 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).