What is fatty acid

   What are fatty acids?

•  Fatty acids are carboxylic acids with long hydrocarbon chain. They are simplest form of lipids. General formula :  R-(CH₂)_n- COOH.

• Fatty acids usually consist of 12-20 molecules of C. They are divided into 2 portions- Hydrophobic tail & Hydrophilic head. Although they contain polar carboxylic group in their structure, however they're insoluble in water. Because of their hydrophobic portion is much bigger than the hydrophilic portion.

Ø Physical  Properties  of Fatty acids

 1. Solubility  in  water :

•       Fatty acids containing  up to  6 carbons are completely soluble in water.  
•       Longer  chain fatty  acids are  insoluble  in water  but  soluble in fat solvents.  

2.  Physical  state  at  room  temperature :  

•     The  lower  members  of  saturated fatty acids are liquid  at  room temperature  & volatile. They  have irritant  odour  & bad taste.  
•       Those higher  than  10  carbons are  solids.  
•       Unsaturated long chain fatty acids are  liquids  due to  the  presence of cis  double bonds 

Ø   Nomenclature of Fatty Acids

Carbon atoms are numbered from the carboxyl carbon (carbon No. 1). The Carbon atoms adjacent to the carboxyl carbon are numbered as 2, 3…etc & are also known as α, β…etc, carbons respectively. 

The terminal methyl group is known as the ω(omega) carbon which is used to indicate the site of a double bond. For example: ω9 indicates a double bond on the 9th C counting from the terminal methyl group. 

Examples:

Also read :

Classification of fatty acids
Difference between fats and oils
What's cholesterol | It's sources, classification, significance etc