What are covalent bonds and organic molecules?
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Another way that atoms can bond with each other is by sharing electrons. This is a fascinating event whereby atoms share electrons between them to form a stable union. In Covalently Bonded Molecules Figure you see a straight line connecting atoms that are bonded in this manner. |
Probably the best examples of this type of bonding are the organic molecules, which refers to those molecules that contain carbon atoms. Organic also refers to that which is living. Therefore, the most important molecules of life must be carbon based. In fact, a large portion of this book discusses organic molecules, such as proteins, carbohydrates, fats, cholesterol, nucleic acids, and vitamins. In the Covalently Bonded Molecules Figure you can see that methane (CH4) and carbon dioxide (CO2) are organic molecules while water (H2O) is not.
What is the design of molecules?
One limitation of an ink-and-paper representation of molecules is that it often fails to truly capture the three-dimensional beauty of molecules. For example, DNA molecules exist in a spiral staircase design, while many protein molecules appear to be all bunched (or globbed) up. The three-dimensional design of a molecule helps determine what that molecule can do (its properties). Furthermore, we will see that many of the important molecules in our body are actually combinations of smaller molecules. For instance, proteins are made from amino acids, and fat molecules are made from fatty acids and glycerol.
How do molecules interact with one another?
Molecules in our body, or anywhere else in nature, mingle among one another. And, if things are right, they can interact. When molecules interact the process is called a chemical reaction. For instance, in the reaction below, A and B are substances that react and are called reactants. As a result of this chemical reaction different substances are produced and are called products. In the chemical reaction below the products are C and D.
A + B ----> C + D
The reaction arrow (→) separating the reactants and products merely shows which way the chemical reaction will proceed. A reaction may proceed in only one direction or it may be reversible, whereby the reaction will proceed in either direction. A reversible-reaction arrow looks like you might expect (<---->). If there is a number (coefficient) in front of reacting or produced substances this merely tells us how many molecules of a substance must react or be produced in order for the chemical reaction to make sense or be “balanced.”
