Question

Indicate the wrong statement according to valence bond therory:

• A. a sigma bond is stronger then $\pi$ bond
• B. p-orbitals always have only sidewise overlapping
• C. s-orbitals never form $\pi$ - bonds
• D. there can be only one sigma bond between two atoms

Answer 1

The correct option is B p-orbitals always have only sidewise overlapping

Postulates of Valence Bond Theory-

• The overlapping of two half-filled valence orbitals of two different atoms results in the formation of the covalent bond. The overlapping causes the electron density between two bonded atoms to increase. This gives the property of stability to the molecule.
• In case the atomic orbitals possess more than one unpaired electron, more than one bond can be formed and electrons paired in the valence shell cannot take part in such a bond formation.
• A covalent bond is directional. Such a bond is also parallel to the region of overlapping atomic orbitals.
• Based on the pattern of overlapping, there are two types of covalent bonds: sigma bond and a pi bond. The covalent bond formed by sidewise overlapping of atomic orbitals is known as pi bond whereas the bond formed by overlapping of atomic orbital along the inter nucleus axis is known as a sigma bond. A pi bond is stronger than sigma bonds.
• Hence option B is wrong statement.