I. Introduction
Identifying covalent compounds can be a challenging task, especially for beginners. It is easy to confuse covalent compounds with ionic compounds, which have different properties. Covalent compounds are made up of atoms that share electrons, while ionic compounds are made up of positively and negatively charged ions that attract each other. In this article, we explore the basics of covalent bonding, the properties of covalent compounds, how to identify them, and some common examples.
II. The Basics of Covalent Bonding
Covalent bonding occurs when two nonmetal atoms share electrons to form a molecule. The shared electrons are located in the atoms’ outermost shell, which is also known as the valence shell. The electrons are shared to complete the valence electron shell of both atoms and create a stable molecule. Covalent bonds can occur between two of the same atoms, such as in diatomic molecules like oxygen gas (O2) or can occur between different atoms, such as in water (H2O) and carbon dioxide (CO2).
Covalent compounds have several main characteristics. They have low melting and boiling points, are often gases or liquids at room temperature, and many are insoluble in water but soluble in organic liquids. These characteristics are different from those of ionic compounds, which are often solid at room temperature, have high boiling and melting points, and are quite soluble in water.
Some of the most common covalent compounds include carbon monoxide (CO), hydrogen chloride (HCl), and ammonia (NH3). Additionally, organic molecules like carbohydrates, proteins and lipids are also covalent compounds.
III. Properties of Covalent Compounds
Covalent compounds have unique properties that can be attributed to their bonding configuration. One key property is that they have a lower melting and boiling point than ionic compounds. This is because the molecules of covalent compounds are held together by weak intermolecular forces between the molecules rather than strong electrostatic forces between ions.
Furthermore, covalent compounds are poor conductors of electricity and generally are insoluble in water. The lack of conductivity is due to the absence of charged particles like ions, while the insolubility is mainly due to the molecules’ size and polarity, which prevents interaction with the polar water molecules.
IV. How to Identify Covalent Compounds
To identify covalent compounds from their molecular formulae, we can use several rules. Most covalent compounds are made up of nonmetals as these elements typically engage in covalent bonding more readily than metals. Furthermore, covalent compounds typically have two or more different elements in their formulae, such as H2O, CO2, and HCl.
One technique to detect covalent compounds is to observe the electronegativity of the atoms. Nonmetals tend to have a high electronegativity, meaning that they pull shared electrons towards themselves. As a result, pairs of compounds that utilize nonmetals will often share electrons unequally. If the difference in electronegativity between the two atoms is small (<1.5), there is a high likelihood that the compound is covalent. Conversely, compounds with a large electronegativity difference between the two atoms are ionic, such as NaCl.
V. Common Examples of Covalent Molecules
There are several known covalent molecules, some of which we encounter in our daily lives. Water (H2O), for example, is a covalent molecule that has two hydrogen atoms covalently bonded to an oxygen atom. Additionally, carbon dioxide (CO2) is a covalent molecule made up of one carbon atom and two oxygen atoms.
Other examples of covalent molecules include nitrogen gas (N2), ammonia (NH3), methane (CH4), phosphorus pentoxide (P4O10), and ethylene (C2H4).
VI. Covalent vs. Molecular Bonding
Covalent bonding and molecular bonding are different concepts with different properties. Covalent bonding involves the sharing of electrons between two atoms, while molecular bonding is a broader term that refers to how atoms are held together to form a molecule. Molecular bonding includes covalent bonding and other types of bonding, such as hydrogen bonding and ionic bonding.
Covalent bonding occurs when the two atoms share the electrons equally and the resulting molecule has no negative or positive charges. In contrast, molecular bonding may or may not have charges, depending on whether other types of bonding have occurred.
VII. Applications of Covalent Compounds
Covalent compounds have diverse applications in several fields, including pharmacy, polymer chemistry, and electronics. For example, pharmaceutical companies use covalent compounds in drug discovery and development, such as the anti-viral medication acyclic nucleoside phosphonate.
In polymer chemistry, covalent compounds are essential for the production of synthetic polymers used in products such as plastics, fibers, and films. Examples of covalent polymers include nylon, polyethylene, Teflon, and polyacrylamide.
In electronics, covalent compounds are used to create and program integrated circuits and computer memory. For example, polycarbonate can be used to make compact discs and DVDs, while arsenic triselenide (As2Se3) is a compound used to create rewritable CD and DVD discs.
VIII. Conclusion
In conclusion, covalent compounds are molecules made up of non-metal atoms that share electrons. They have lower melting and boiling points than ionic compounds and are poor conductors of electricity. We can identify them by paying attention to the formula of the molecule and the nature of the elements. Understanding covalent compounds is essential in identifying different types of chemical compounds, and their utility in diverse fields such as polymer chemistry, electronics, and medicine makes them invaluable.