Basics of Organic Chemistry

 Basics of Organic Chemistry

Organic chemistry is a part of our lives at every moment. Organic molecules comprise the tissue of plants as mighty as the redwoods, convey signals from one neuron to the next in animals, store the genetic information of life, and are the food we eat each day. The growth of living things from microbes to elephants rests on organic reactions, and organic reactions provide the energy that drives our muscles and our thought processes. 

Our lives depend on organic chemistry in many other ways as well. Every article of clothing we wear is a product of organic chemistry, whether the fibers are natural or synthetic. Hardly a minute goes by when we’re not using something made of organic molecules, such as a pen, a computer keyboard, a music player, or a cellular phone.

Basics of Organic Chemistry
Basics of Organic Chemistry

 We view display screens made of organic liquid crystal arrays. Natural organic polymers comprise wood and the paper we read. Natural and synthetic organic molecules enhance our health. There is not a single aspect of our lives that is not in some way dependent on organic chemistry. But what is organic chemistry? • Organic chemistry is the chemistry of compounds that contain the element carbon. Clearly, carbon compounds are central to life on this planet. Carbon as an element, however, has its origin elsewhere.

Some 14.5 billion years ago the big bang formed hydrogen and helium, the lightest elements. Further nuclear reactions in stars transmuted these elements into heavier ones, including carbon, nitrogen, oxygen, sulfur, phosphorus, and most others in the periodic table. Massive explosions called supernovae scattered the elements in the universe, and over time heavy elements coalesced to form planets and other celestial bodies. 

Through processes not understood but about which there continues to be much research, simple molecules formed, eventually including organic molecules that could support life—the nucleic acids that make up DNA and RNA, the amino acids that comprise proteins, carbohydrates such as glucose, and other types of molecules. It is from elegant molecular building blocks like these that the incredible richness of chemistry and life has evolved. So, in the truest sense we living creatures are composed of stardust, and without supernovae not only would there be no organic chemistry, there would be no life.

Development of the Science of Organic Chemistry

 The science of organic chemistry began to flower with the demise of a nineteenth century theory called vitalism. According to vitalism, organic compounds were only those that came from living organisms, and only living things could synthesize organic compounds through intervention of a vital force. Inorganic compounds were considered those compounds that came from nonliving sources. 

Friedrich Wohler, however, discovered in 1828 that an organic compound called urea (a constituent of urine) could be made by evaporating an aqueous solution of the inorganic compound ammonium cyanate. With this discovery, the synthesis of an organic compound, began the evolution of organic chemistry as a scientific discipline.

Despite the demise of vitalism in science, the word “organic” is still used today by some people to mean “coming from living organisms” as in the terms “organic vitamins” and “organic fertilizers.” The commonly used term “organic food” means that the food was grown without the use of synthetic fertilizers and pesticides. An “organic vitamin” means to these people that the vitamin was isolated from a natural source and not synthesized by a chemist. While there are sound arguments to be made against using food contaminated with certain pesticides, while there may be environmental benefits to be obtained from organic farming, and while “natural” vitamins may contain beneficial substances not present in synthetic vitamins, it is impossible to argue that pure “natural” vitamin C, for example, is healthier than pure “synthetic” vitamin C, since the two substances are identical in all respects. In science today, the study of compounds from living organisms is called natural products chemistry.

Elements are made up of atoms. An atom  consists of a dense, positively charged nucleus containing protons and neutrons and a surrounding cloud of electrons. Each proton of the nucleus bears one positive charge; electrons bear one negative charge. 

Neutrons are electrically neutral; they bear no charge. Protons and neutrons have nearly equal masses (approximately 1 atomic mass unit each) and are about 1800 times as heavy as electrons. Most of the mass of an atom, therefore, comes from the mass of the nucleus; the atomic mass contributed by the electrons is negligible. 

Most of the volume of an atom, however, comes from the electrons; the volume of an atom occupied by the electrons is about 10,000 times larger than that of the nucleus. The elements commonly found in organic molecules are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur, as well as the halogens: fluorine, chlorine, bromine, and iodine. 

Each element is distinguished by its atomic number (Z), a number equal to the number of protons in its nucleus. Because an atom is electrically neutral, the atomic number also equals the number of electrons surrounding the nucleus.

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