Among the most important compounds that are found in the earth’s biosphere is water. Water is vital in supporting millions of lives of both plants and animals that grace the land. As a matter of fact, in this sphere, it is the most abundant compound. In appearance, water is a colorless and odorless compound exhibiting unique physical properties. These properties are owed to its “electronic structure, bonding and chemistry” (Rolands 33). Significantly, its affinity to react with a myriad of elements renders it impure at any one given time. Against this backdrop, in the thesis statement, we explore the physical/chemical properties of water and analyze how unique they are. As such, in this essay, we explore the structure and bonding, molecular symmetry and amphiprotic properties.
The molecular formula of pure water is portrayed as H2O. This molecule is unique in itself; the bond length between the oxygen and one of the hydrogen atoms (O-H) is 0.096 nm. The repulsion between two lone pairs is the reason that the molecule assumes a wedge-shaped structure with an angle of 104.5o between the O-H bonds (see the fig. 1 below).
In order to understand why the structure assumes the above shape, it is important to note that the atomic structure of oxygen requires extra two electrons for it to fill its outer energy level. When the atom bonds with hydrogen atoms, two lone pairs result (see fig. 2 below).
The two lone pairs repel each with a greater force than they do for the O-H bonds. As a consequence, the O-H bonds are pushed much closer to each other to form a wage-shaped structure (fig. 1) with an angle much less than 109o.
Considering the structure in the figure above (fig. 1), it is evident that a molecule of water has a line of symmetry that can be traced through the water molecule, acting as a bisector of the angle between the two O-H bonds. Another line of symmetry that is visible on a three-dimensional structure is that which forms a mirror image containing three atoms. Moreover, the molecule remains uninterrupted when turned at an angle of 180o, portraying that the molecule has a two-fold rotation plane. Both mirror planes “contain the rotation axis, and this type of symmetry belongs to the point group C2v” (Utz 3). A point group is defined by the number of symmetry atoms that are organized in a particular fashion. Molecules exhibit diverse point group characteristics which can serve as a model for classification. Those molecules that belong to a common group exhibit analogous spectroscopic behavior. Just like it has been mentioned before, H2O belongs to point group Cv2. This group includes compounds like CH2=O and CH2Cl2.
One interesting topic that continues to baffle chemists is the science of equilibria, a science that analyzes acid-base behaviors. Water molecule is unique in the sense that they can form either a weak acid or base. This is owed to the fact that it has the ability to “accept (H3O+) or donate a proton (OH–)” (Utz 5). As such, water is considered to be amphiprotic. This behavior basically renders water a buffer solution.
In a conclusion, this essay has highlighted some physical/chemical properties of water that make it a unique compound. These properties influence the behavior of water in chemical reactions.
Works Cited
Rolands, Smith. Conquering Chemistry. South Melbourne, Victoria: Thomson Learning, 2004. Print.
Utz, Jeffrey. Chemistry of Water. New York, NeW York University Press, 2007. Print.