Chemical Thermodynamics

Chemical Bonds

Atoms are composed of three components, electrons, neutrons, and protons. The protons and neutrons form the central core, the nucleus, and electron orbitals interact with each other to form chemical bonds in such a way that each orbital is filled with electrons. In many chemicals, this can only be accomplished by sharing the available electrons.     To fill their orbitals, carbon atoms must share 4 electrons. To do this, they need to form 4 chemical bonds. Nitrogen atoms must share 3 electrons, so they typically form 3 chemical bonds. Hydrogen atoms must share 1 electron, so they typically form one chemical bond. Oxygen atoms must share 2 electrons, so they typically from two bonds.

   By knowing how many chemical bonds each atom requires, it is possible to predict chemical structures. For example, every water molecule has 2 hydrogen atoms and 1 oxygen atom. The oxygen atom is satisfied because it shares 2 electrons, one with each hydrogen atom. Likewise, both hydrogen atoms are satisfied because each shares one electron with the single oxygen atom (figure 6.1A).

Multiple Bonds

In many cases, if atoms cannot satisfy their requirements for sharing electrons, they will form double and triple bonds. For example, oxygen forms a double bond with itself. Since oxygen desires two electrons, by forming a double bond instead of a single, each oxygen atom in an oxygen molecule is satisfied (both have 2 bonds and share 2 electrons).

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