Octahedral

Octet rule

Oil hydrogenation

Oils                                          

Oligosaccharides

Oppenheimer

Optimal pH value

Orbital                            

Organic acids

Organic Chemistry

Organic Compound

Osmotic pressure

Oxidation                                                     

Oxidation

Oxidation number 

Oxidation reduction reaction

Oxidizing agent     

Oxoacid

Ozone