The Three Chemical Bonds-Cal Hatton

A bond is formed when electrons from two atoms interact with each other and their atoms become joined. The electrons that interact with each other are VALENCE ELECTRONS, the ones that reside in the outermost electron shell of an atom. There are two main types of bonding discussed here. A COVALENT BOND results when two atoms "share" valence electrons between them. Covalent bonds involve a complete sharing of electrons and occurrs most commonly between atoms that have partially filled outer shells or energy levels. Thus if the atoms are similar in negativity then the electrons will be shared. Carbon forms covalent bonds. The electrons are in hybrid orbitals formed by the atoms involved as in this example: ethane. Diamond is strong because it involves a vast network of covalent bonds between the carbon atoms in the diamond. An IONIC BOND occurs when one atom gains a valence electron from a different atom, forming a negative ion (ANION) and a positive ion (CATION), respectively. These oppositely charged ions are attracted to each other, forming an ionic bond. Ionic bonds arise from elements with low electronegativity(almost empty outer shells) reacting with elements with high electronegativity (mostly full outer shells). In this case there is a complete transfer of electrons. A well known example is table salt, sodium chloride. Sodium gives up its one outer shell electron completely to chlorine which needs only one electron to fill its shell. Thus, the attraction between these atoms is much like static electricity since opposite charges attract. There is a third type of bonding, called METALLIC BONDING. As the name implies, metallic bonding usually occurs in metals, such as copper. A piece of copper metal has a certain arrangement of copper atoms. The valence electrons of these atoms are free to move about the piece of metal and are attracted to the positive cores of copper, thus holding the atoms together.