Introduction to Organic Chemistry | Chemistry Class 11 - NEET PDF Download

General Introduction

• The branch of chemistry which deals with Carbon and its derivatives is called Organic chemistry.
• Organic chemistry began to emerge as a science about 200 years ago. By the late eighteenth century, substances were divided into two classes called organic and inorganic compounds.

• Organic compounds were obtained from plants and animals.
• Organic compounds were more difficult to work within the laboratory and decompose easily.
• The hydrides of carbon (hydrocarbons) and their derivatives are called organic compounds. The branch of chemistry which deals with these compounds is called organic chemistry.
• Berzelius (1808) defined organic chemistry as the chemistry of substances found in living matter and gave the vital force theory.
• The synthesis of urea, the first organic compound synthesised in the laboratory, by Wohler who gave the death blow to the vital force theory.

• Acetic acid is the first organic compound synthesized from its elements.

Tetravalency of Carbon: Shapes of Organic Compounds

(a) Catenation

• It is the tendency of self combination and is maximum in carbon.
• A carbon atom can combine with other carbon atoms by single, double, or triple bonds.
• Thus, Carbon forms more compounds than the other elements.

(b) Tetravalency and Small Size 

• Carbon is tetravalent, is capable of bonding with four other C atoms or some other monovalent atoms. 
• Carbon can form a compound with oxygen, hydrogen, chlorine, sulphur, nitrogen and phosphorus.
• These compounds have specific properties depending upon the nature of the element or group attached to the carbon.
• Furthermore, these compounds are exceptionally stable because of the small size of carbon.

General Characteristics of Organic Compounds

1. These are the compounds of carbon with H, O, N, S, P, F, CI, Br and I.
2. These are generally found in living organisms. e.g., carbohydrates, proteins etc.
3. These may be gases, liquids or solids.
4. Being covalent in nature, these have a low boiling point and melting point and soluble in organic solvents.
5. These are generally volatile and inflammable.
6. They do not conduct electricity because of the absence of free ions.
7. They possess distinct colour and odour.

Structural Representations of Organic Compounds

• Complete Structural Formula – Full structural equations show all the atoms in a molecule, the types of bonds that bind them, and how they are interconnected.
• Condensed Structural Formula – The Condensed structural formula is used to save space, structural formulas are conveniently abbreviated as condensed structural formulas.
• Bond Line Structural Formula – A bond-line structure is a less cluttered drawing than a condensed structural formula. However, to understand the simplified bond-line structure, the reader has to mentally add many more features to comprehend the overall structure.