organic compounds are mainly composed of ten elements. These are C, H, O, N, S, P, F, Cl, Br and I. compounds obtained from plants such as starch, sugar, cellulose, oils, fats, etc., contain mainly carbon, hydrogen and oxygen while those obtained from animals such as urea, uric acid, proteins, etc., contain nitrogen besides carbon, hydrogen and oxygen. Certain organic compounds are very complex and possess very high molecular masses. For instance, molecular masses for proteins range from several thousands to over a million.
ii) Quadri-covalency of carbon:- the carbon present in organic compounds is always quadric-covalent in nature. It combines with other atoms by covalent bonds. This gives rise to the identical behavior of all organic compounds. A carbon atom can link with other carbon atom by single, double or triple bonds. The property of catenation is very strong in organic compounds.
Organic compounds are essentially covalent compounds. They show characteristics of covalent compounds.
a) They are volatile in nature.
b) They have low melting and boiling points.
c) They are generally insoluble in water but soluble in organic solvents.
d) They are bad conductors of electricity.
e) They do not furnish ions. They show molecular reactions.
In general, the reactions of organic compounds are slow. They never proceed to completion and their yields are generally of low order.
iii) Colour and odour:- Organic compounds possess distinct colour and odour.
iv) Action of heat:- Organic compounds are not stable towards heat. They decompose on heating at high temperature. Some of them decompose on heating leaving a black residue.
v) Combustion:- Organic compounds readily burn in air. They burn with smoky or non-smoky flame. One of the products of combustion is always carbon dioxide.
vi) Homologous series:- Organic compounds have been classified into many classes each having the same functional group. The classes are known as homologous series. The compounds belonging to the same class show similar chemical properties.
vii) Polymerism: - Quite a number of organic compounds exhibit polymerism (when a molecular formula of an organic compound is a simple multiple of the other). For example, benzene (C6H6) is a polymer of acetylene (C2H2).
viii) Isomerism:- Organic compounds show the phenomenon of isomerism