Question Video: Identifying What Is and What Is Not a Sigma (𝜎) Bond Chemistry • Second Year of Secondary School

Video Transcript

A 𝜎 bond is created when specific combinations of atomic orbitals overlap. Which of the following occurrences does not result in the formation of a 𝜎 bond? (A) A hybrid sp orbital overlapping with another hybrid sp orbital, (B) an s orbital overlapping with a p orbital, (C) a p orbital overlapping with another p orbital side-by-side, (D) an s orbital overlapping with another s orbital, (E) a p orbital overlapping with another p orbital end-to-end.

Sigma bonds, often noted with the lowercase Greek letter, are formed by the end-to-end overlap of orbitals. It doesn’t matter which two orbitals are overlapping as long as they overlap end-to-end. Two s orbitals overlapping can create a 𝜎 bond or an s orbital can overlap with a p orbital. A 𝜎 bond results from the s orbital overlapping any of the hybrid orbitals. 𝜎 bonds also result from p orbitals overlapping end-to-end or a p orbital overlapping with any of the hybrid orbitals. Any of the hybrid orbitals can also overlap with each other end-to-end.

Any combination of two orbitals that overlap end-to-end such as these will result in a 𝜎 bond. But if we have two orbitals overlapping side-by-side, like these two p orbitals, the resulting bond is a 𝜋 bond, not a 𝜎 bond. So answer choice (C), a p orbital overlapping with another p orbital side-by-side, would result in the formation of a 𝜋 bond not a 𝜎 bond. So it’s the correct answer.