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Chemistry LibreTexts

1: Structure and Bonding

  • Page ID
    31366
  • Chapter Objectives

    This chapter provides a review of material covered in a standard freshman general-chemistry course through a discussion of the following topics:

    • the differences between organic and inorganic chemistry.
    • the shapes and significance of atomic orbitals.
    • electron configurations.
    • ionic and covalent bonding.
    • molecular orbital theory.
    • hybridization.
    • the structure and geometry of the compounds methane, ethane, ethylene and acetylene.

    • 1.1: Prelude to Structure and Bonding
      Organic compounds contain carbon atoms bonded hydrogen and other carbon atoms. Organic chemistry studies the properties and reactions of organic compounds.
    • 1.2: Atomic Structure - The Nucleus
      Atoms are comprised of protons, neutrons and electrons. Protons and neutrons are found in the nucleus of the atom, while electrons are found in the electron cloud around the nucleus. The relative electrical charge of a proton is +1, a neutron has no charge, and an electron’s relative charge is -1. The number of protons in an atom’s nucleus is called the atomic number, Z. The mass number, A, is the sum of the number of protons and the number of neutrons in a nucleus.
    • 1.3: Atomic Structure - Orbitals
      An atomic orbital is the probability description of where an electron can be found. The four basic types of orbitals are designated as s, p, d, and f.
    • 1.4: Atomic Structure - Electron Configurations
      The order in which electrons are placed in atomic orbitals is called the electron configuration and is governed by the aufbau principle. Electrons in the outermost shell of an atom are called valence electrons. The number of valence electrons in any atom is related to its position in the periodic table. Elements in the same periodic group have the same number of valence electrons.
    • 1.5: Development of Chemical Bonding Theory
      Lewis Dot Symbols are a way of indicating the number of valence electrons in an atom. They are useful for predicting the number and types of covalent bonds within organic molecules. The molecular shape of molecules is predicted by Valence Shell Electron Pair Repulsion (VSEPR) theory. The shapes of common organic molecules are based on tetrahedral, trigonal planar or linear arrangements of electron groups.
    • 1.6: The Nature of Chemical Bonds - Valence Bond Theory
      Covalent bonds form as valence electrons are shared between two atoms. Lewis Structures and structural formulas are common ways of showing the covalent bonding in organic molecules. Formal charge describes the changes in the number of valence electrons as an atom becomes bonded into a molecule. If the atom has a net loss of valence electrons it will have a positive formal charge. If the atom has a net gain of valence electrons it will have a negative formal charge.
    • 1.7: sp³ Hybrid Orbitals and the Structure of Methane
      The four identical C-H single bonds in methane form as the result of sigma bond overlap between the sp3 hybrid orbitals of carbon and the s orbital of each hydrogen.
    • 1.8: sp³ Hybrid Orbitals and the Structure of Ethane
      The C-C bond in ethane forms as the result of sigma bond overlap between a sp³ hybrid orbital on each carbon. and the s orbital of each hydrogen. The six identical C-H single bonds in form as the result of sigma bond overlap between the sp³ hybrid orbitals of carbon and the s orbital of each hydrogen.
    • 1.9: sp² Hybrid Orbitals and the Structure of Ethylene
      The C=C bond in ethylene forms as the result of both a sigma bond overlap between a sp2 hybrid orbital on each carbon and a pi bond overlap of a p orbital on each carbon
    • 1.10: sp Hybrid Orbitals and the Structure of Acetylene
      The carbon-carbon triple bond in acetylene forms as the result of one sigma bond overlap between a sp hybrid orbital on each carbon and two pi bond overlaps of p orbitals on each carbon.
    • 1.11: Hybridization of Nitrogen, Oxygen, Phosphorus and Sulfur
      The atomic orbitals of nitrogen, oxygen, phosphorus and sulfur can hybridize in the same way as those of carbon.
    • 1.12: The Nature of Chemical Bonds- Molecular Orbital Theory
      Molecular Orbital theory (MO) is a more advanced bonding model than Valence Bond Theory, in which two atomic orbitals overlap to form two molecular orbitals – a bonding MO and an anti-bonding MO.
    • 1.13: Drawing Chemical Structures
      Kekulé Formulas or structural formulas display the atoms of the molecule in the order they are bonded. Condensed structural formulas show the order of atoms like a structural formula but are written in a single line to save space. Skeleton formulas or Shorthand formulas or line-angle formulas are used to write carbon and hydrogen atoms more efficiently by replacing the letters with lines. Isomers have the same molecular formula, but different structural formulas
    • 1.S: Structure and Bonding (Summary)