Skip to main content
Chemistry LibreTexts

4: Atoms, Elements, and the Periodic Table

  • Page ID
    • 4.1: 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.
    • 4.2: The Elements
      This section will cover the importance of the elements, and further discuss element naming.
    • 4.3: 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.
    • 4.4: Atomic Theory
      Chemistry is based on the modern atomic theory, which states that all matter is composed of atoms. Atoms themselves are composed of protons, neutrons, and electrons. Each element has its own atomic number, which is equal to the number of protons in its nucleus. Isotopes of an element contain different numbers of neutrons. Elements are represented by an atomic symbol. The periodic table is a chart that organizes all the elements.
    • 4.5: Defining Isotopes
      Elements can be identified by their atomic number and mass number. Isotopes are atoms of the same element that have different masses.
    • 4.6: Atomic Masses
      Atoms have a mass that is based largely on the number of protons and neutrons in their nucleus.
    • 4.7: Arrangements of Electrons
      Electrons are organized into shells and subshells about the nucleus of an atom.
    • 4.8: Orbital Shape
    • 4.9: 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.
    • 4.10: Ions - Losing and Gaining Electrons
      Atom may lose valence electrons quite to obtain a lower shell that contains an octet. Atoms that lose electrons acquire a positive charge as a result because they are left with fewer negatively charged electrons to balance the positive charges of the protons in the nucleus. Positively charged ions are called cations. Most metals become cations when they make ionic compounds.
    • 4.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.