A sigma bond (σ bond) is a type of chemical bond. It is the strongest one of the covalent type. In a sigma bond, the atomic orbitals from two atoms which are nearby go one on top of each other. This is different from a pi bond where they touch sideways. This is why a sigma bond is stronger. Sigma bonds can involve s, p, d or f orbitals. They must however be of the right symmetry to be able to form the bond.
Since the σ bond is strong, the bonding orbital is low in energy. This also means that the antibonding orbital σ* is high in energy.
References[change | change source]
- Moore, John; Stanitski, Conrad L.; Jurs, Peter C.. Principles of Chemistry: The Molecular Science. http://books.google.co.in/books?id=ZOm8L9oCwLMC&pg=PA324&lpg=PA324&dq=sigma+bond+stronger+than+pi&source=bl&ots=ps9tk8CuCx&sig=phaUUfoNHzSp3XN1MWR7YENyVBE&hl=en&sa=X&ei=lRaqT9PMA8bprAfu3pXsAQ&ved=0CGsQ6AEwBTgU#v=onepage&q=sigma%20bond%20stronger%20than%20pi&f=false.