Characteristics of organic substances

The structure of methane by pictorial representation of a Lewis diagram showing the sharing of electronpairs between atomic nuclei in a covalent bond. Please do not form the impression from the diagram that the real picture is two-dimensional, because this is not the case.
Methane - a carbon atom bonded to 4 hydrogen atoms
Organic compounds are generally covalently bonded. This allows for unique structures such as long carbon chains and rings.
Isohexane - a branched-carbon chain
Cyclohexane - a ringed hydrocarbon
The reason carbon is excellent at forming unique structures and that there are so many carbon compounds is that carbon atoms form very stable covalent bonds with one another (catenation). In contrast to inorganic materials, organic compounds typically melt, boil, sublimate, or decompose below 300 °C. Neutral organic compounds tend to be less soluble in water compared to many inorganic salts, with the exception of certain compounds such as ionic organic compounds and low molecular weight alcohols and carboxylic acids where hydrogen bonding occurs.
Organic compounds tend to dissolve in organic solvents which are either pure substances like ether or ethyl alcohol, or mixtures, such as the paraffinic solvents such as the various petroleum ethers and white spirits, or the range of pure or mixed aromatic solvents obtained from petroleum or tar fractions by physical separation or by chemical conversion. Solubility in the different solvents depends upon the solvent type and on the functional groups if present. Solutions are studied by the science of physical chemistry. Like inorganic salts, organic compounds may also form crystals. A unique property of carbon in organic compounds is that its valency does not always have to be taken up by atoms of other elements, and when it is not, a condition termed unsaturation results. In such cases we talk about carbon carbon double bonds or triple bonds. Double bonds alternating with single in a chain are called conjugated double bonds. An aromatic structure is a special case in which the conjugated chain is a closed ring.