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Structure Of Water Molecule - Chemistry Of Water - Properties Of Water - Composition Of Water

In this video we discuss the structure of water. We cover how and why is water a solvent to other substances, and how the ability of water to act as a solvent makes it a great transporting agent in the body. Transcript and notes The structure of water The chemistry of water Water is an inorganic molecule that is the most important compound in the body. In fact, a normal adult’s body weight is made up of 50% or more of water. A molecule of water has one oxygen atom covalently bonded to 2 hydrogen atoms. Covalent bonds being chemical bonds that are formed by the sharing of one or more pairs of electrons by the outer energy levels or shells of two atoms. Water molecules are also polar molecules, even though the oxygen atom shares electrons with the hydrogen atoms, the electrons are not shared equally within the molecule. This gives the oxygen side of the molecule two partial negative charges, and each of the hydrogen’s a slightly positive charge. This means that each water molecule can form up to 4 hydrogen bonds with adjacent water molecules. Hydrogen bonds are the result of an unequal charge distribution on a molecule, these molecules are said to be polar. This property allows water to act as a very effective solvent, which means it is able to dissolve or break apart many other substances. Substances that do dissolve or break apart in water are called hydrophilic, which means water loving. Non polar substances that do not dissolve in water are called hydrophobic, or water fearing. Some substances such as glucose molecules dissolve and remain intact in water, as water molecules surround the substance forming a hydration shell around the molecule. Some substances dissolve and dissociate or break apart in water. Table salt or NaCl, when added to water will dissociate to form positive Na ions and negative Cl ions, with hydration shells forming around each ion. This property of water allows it to function as a transporter, as water based fluids such as blood transport substances dissolved in water throughout the body. Non polar hydrophobic substances such as fats and cholesterol that do not bond with water must be enclosed within a transport protein molecule to be transported within blood. Other notes Water also absorbs and gives up heat slowly, which means it retains a relatively constant temperature. This property plays an important role in maintaining body temperature. This can be seen during exercise, as water or sweat is evaporated from the surface of the skin. Water also functions as a lubricant moistening food making it easier to swallow and decreasing friction as is the case with synovial fluid located within certain joints. Water acts as a cushion in some areas of the body, as the fluid surrounding the brain and spinal cord are water based. Water helps keep tissues moist, such as the eyes, nose and throat, enabling them to function properly as well as helping keep skin from drying and cracking. And water helps to excrete wastes in the body, as some unwanted substances are eliminated through urine. Timestamps 0:00 Water in the body 0:12 Chemical structure of a water molecule 0:55 Water can act as a solvent 1:41 Water can act as a transporter