Lesson 3 Introduction of Organic Chemistry

3.1 The Origins of Organic Chemistry

The term organichas acquired a variety of meanings during the 20th century，apart from its traditional usage to describe the branch of chemistry you are beginning to study here. For instance，some produce in the local store is described as organically grown，or we talk about organic foods . This label often means that a vegetable or fruit is grown under conditions where nutrients made by synthetic means are not added to the soil and that the nutrients come from compost instead. Another use of the word organicwas popularized by Frank Lloyd Wright，who coined the term organic architectureto describe designs in which the exterior space of a building would blend with the surrounding environment of nature in a harmonious way. The word organicoften attaches some notion of life or naturalness to an object.

In this way，the term organic chemistry was applied during the early 1800s to the study of substances related to living，or once-living，organisms. Inorganic was used to designate those substances such as rocks and minerals that have no life. But as time passed，differentiating between substanes that came from plants and animals and those that originated from mineral sources became more difficult. Instead，materials began to be defined on the basis of their physical properties. Then，it became more important whether materials have high or low melting points，are soluble or insoluble in water，or are liquid，solid or gas.

Using these criteria，chemists soon realize that compounds containing carbon share many of the same properties. So，after isolating and characterizing literally millions of substances over the last two centuries，we have come to define organic chemistry as the chemistry of substances containing carbon. Almost all containing carbon falls into the classification of organic chemicals.

The field of organic chemistry is very broad，encompassing structures and reactions of several million molecules. It is an important area for study and research for many reasons，two of which will be mentioned here. First，the structures of organic molecules are now very well understood，and new types of molecules are readily prepared by rational approaches. This ability to make new substances with predictable structures and properties is one of the most important aspects that separate organic chemistry from many other branches of chemistry，physics and biology. The development of new drugs and materials for industrial and biomedical applications continues to require trained chemists who are interested in chemical synthesis. Second，the essential processes of biology are chemical reaction of organic substances. To discern how life processes occur，we must understand the fundamentals of organic chemistry.