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Chemistry LibreTexts

4: Valence Electrons and Bonding

  • Page ID
    • 4.1: Atomic Models of the Twentieth Century
      In 1913, the Danish physicist Niels Bohr proposed a model of the electron cloud of an atom in which electrons orbit the nucleus and were able to produce atomic spectra. Understanding Bohr's model requires some knowledge of electromagnetic radiation
    • 4.2: Understanding Atomic Spectra
      The ground state of an atom is the lowest energy state of the atom. When those atoms are given energy, the electrons absorb the energy and move to a higher energy level. An excited state of an atom is a state where its potential energy is higher than the ground state. When it returns back to the ground state, it releases the energy that it had previously gained often in the form of electromagnetic radiation (although it can be released via heat).
    • 4.3: Atomic Spectroscopy Applications
      Chemists employ atomic spectrophotometers to determine the identify and/or concentration of a metallic species. Samples must be in liquid form before being placed in the analyzer. In order to do this, a chemist will use certain acids (nitric or hydrochloric) to extract the metallic component of a sample. This process is called digestion and will not affect the analysis of the sample.
    • 4.4: Predicting Ion Charges
      Most atoms do not have eight electrons in their valence electron shell. Some atoms have only a few electrons in their outer shell, while some atoms lack only one or two electrons to have an octet. In cases where an atom has three or fewer valence electrons, the atom may lose those valence electrons quite easily until what remains is a lower shell that contains an octet.
    • 4.5: Lewis Dot and Bonding
      Why are some substances chemically bonded molecules and others are an association of ions? The answer to this question depends upon the electronic structures of the atoms and nature of the chemical forces within the compounds. Although there are no sharply defined boundaries, chemical bonds are typically classified into three main types: ionic bonds, covalent bonds, and metallic bonds.
    • 4.6: Ionic Formula Writing
      So far, we have discussed elements and compounds that are electrically neutral. They have the same number of electrons as protons, so the negative charges of the electrons is balanced by the positive charges of the protons. However, this is not always the case. Electrons can move from one atom to another; when they do, species with overall electric charges are formed. Such species are called ions.
    • 4.7: Applications and Solubility of Ionic Compounds
      In determining whether an inorganic chlorine compound will be soluble, chemists refer to a solubility table. Solubility can be altered by manipulating temperature. Typically, many insoluble compounds can be dissolved at higher temperatures.
    • 4.8: Covalent Bonding and Formula Writing
      In ionic bonding, electrons are transferred from one atom to another so that both atoms have an energy-stable outer electron shell. Because most filled electron shells have eight electrons in them, chemists called this tendency the octet rule. However, there is another way an atom can achieve a full valence shell: atoms can share electrons. This type of bonding would be a covalent bond.
    • 4.9: Free Radicals and the Environment
      The majority of molecules or complex ions discussed in general chemistry courses are demonstrated to have pairs of electrons. However, there are a few stable molecules which contain an odd number of electrons. These molecules, called "free radicals", contain at least one unpaired electron, a clear violation of the octet rule. Free radicals play many important roles a wide range of applied chemistry fields, including biology, medicine, and environmental chemistry.
    • 4.10: Free Radicals and Health
      Free radicals can be generated by a number of processes. For example, combustion of any material will produce OH (not hydroxide) free radicals. Once inhaled, OH can enter the body and affect cells. Free radical exposure has been linked to cancer, aging, and a number of autoimmune diseases.
    • 4.11: Applications and Solubility of Covalent Compounds
      Compounds can be classified as being polar on nonpolar. Polar species are soluble in water, while nonpolar species are soluble in oils. Covalent solubility uses the like dissolves like rule. This means that substances with the same type of polarity will be soluble in one another. In addition, compounds with differing polarities will be insoluble in one another.
    • 4.12: Drug Study
      Drug design, often referred to as rational drug design or simply rational design, is the inventive process of finding new medications based on the knowledge of a biological target.
    • 4.13: Arrhenius Acids and Bases
      Acids are very common in some of the foods that we eat. Citrus fruits such as oranges and lemons contain citric acid and ascorbic acid, which is better known as vitamin C (see figure below). Carbonated sodas contain phosphoric acid. Vinegar contains acetic acid. Your own stomach utilizes hydrochloric acid to digest food. Bases are less common as foods, but they are nonetheless present in many household products.
    • 4.E: Valence Electrons and Bonding (Exercises)
      These are homework exercises to accompany Chapter 4 of the Furman University's LibreText for CHE 101 - Chemistry and Global Awareness.