Covalent Bond Examples Covalent Bond Examples A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding. Covalent bonding includes many kinds of interaction, including Ďƒ-bonding, Ď€-bonding, metalto-metal bonding, agostic interactions, and three-center two-electron bonds. The term covalent bond dates from 1939. The prefix co- means jointly, associated in action, partnered to a lesser degree, etc.; thus a "co-valent bond", in essence, means that the atoms share "valence", such as is discussed in valence bond theory. In the molecule H2, the hydrogen atoms share the two electrons via covalent bonding. Covalency is greatest between atoms of similar electronegativities. Thus, covalent bonding does not necessarily require the two atoms be of the same elements, only that they be of comparable electronegativity. Although covalent bonding entails sharing of electrons, it is not necessarily delocalized.
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Examples of Covalent Bonding There are many examples of compounds having covalent bonds, including the gases in our atmosphere, common fuels and most of the compounds in our body. The molecules and ions just mentioned are composed entirely of nonmetals atoms. A point that needs special emphasis is that in molecules or ions made up only of nonmetals atoms, the also are attached by covalent bonds. Methane molecule (CH4) The electronic configuration of carbon is 2,4. It needs 4 more electrons in its outer shell to be like the noble gas neon. To do this one carbon atom shares four electrons with the single electrons from four hydrogen atoms. The methane molecule has four C-H single bonds. Properties of Covalent Bond The properties of covalent compounds are listed below. 1. Covalent compounds are mostly gases and liquids. 2. Covalent crystals tend to be hard and brittle, and incapable of appreciable bending. These facts are understandable in terms of the underlying atomic forces. Since the bonds have well defined directions in space attempts to alter them are strongly restricted by the crystals. 3. The melting and boiling points are usually low as compared to those of ionic crystals. This is because the covalent bond is not so strong as ionic bond and also because the atoms are less powerfully attracted towards each other, the force that attracts them towards each other is called van der waals forces, dipoles etc. Which are quite weaker.
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4. Most of the covalent substances do not conduct electricity because of the non-availability of free electrons or charged ions to carry the current. However certain substances like HCl which exhibit polarity in aqueous solutions behave like ionic substances and allow the passage of electricity through them accompanied by their own decomposition thereby acting as electrolytes. 5. Covalent substances are insoluble in polar solvents like water. However they are soluble in non-polar solvents like benzene, carbon disulphide etc. This is because of the covalent nature of the solvent. However the giant molecules are not soluble in any solvent because of the large size of the molecules. 6. A very interesting property of covalent crystals is the apparent lack of sensitivity of their physical properties of their bonding type. For example, carbon in the diamond structure is the hardest substance and have a very high melting point 3280K. The hardness and melting point decreases as we proceed to other elements. For example, Tin is the very soft element and has very low melting point. Depending on the number of electrons shared, the bond length and bond energy vary. When the number of electrons shared is more, the bond length between the atoms is decreased and bond energy is increased. Diamond, silicon, germanium, silicon carbide, tin and rutile are some examples of covalent crystals.
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