Chapter 10: Unit 6. Properties of organic compounds

Properties of organic compounds: Organic molecules exist as discrete molecules with much weaker intermolecular forces- the forces that exist between molecules, than those seen in ionic compounds. As a result, organic molecules are similar to other covalent compounds with lower melting and boiling points. They can be solid, liquid or gases depending on the molar mass. Higher molecular weight compounds are generally solid and liquid.

Polarity: A covalent bond is a nonpolar when two atoms of identical or similar electronegativity with very small difference. Therefore C-C and C-H bonds are nonpolar. A covalent bond is a polar when a strong electronegative atom is bonded to C (N, O, Cl etc.). Greek symbol δ+ and δ- are used to determine less and more electronegative atoms respectively. In general hydrocarbons are nonpolar, alcohol, aldehydes, ketones and carboxylic acids are polar in nature.

Depending on the polarity organic molecules can be soluble or insoluble in water. Polar organic molecules are soluble and nonpolar organic compounds are insoluble in water.

Chemical reactions of organic molecules happen only on the functional group. Other part of the molecules remain unchanged. The nature of the chemical reactions depend on the nature of the function al groups. Individual physical and chemical properties and reactions will be discussed under separate chapters.