Covalent Bonds: Characteristics and Relationships

This set of flashcards covers the key concepts regarding covalent bonds, their characteristics, relationships between bond order, strength, and length, as well as bond dissociation energy.

What is bond length?

The distance between the nuclei of the two atoms in a bond.

How does bond order relate to bond strength?

Higher bond order results in shorter and stronger bonds between the same two atoms.

What happens to potential energy as two hydrogen atoms approach each other?

Potential energy decreases as hydrogen atoms approach, and is most stable when energy is at a minimum.

What is the bond dissociation energy (BDE)?

The change of enthalpy when one mole of a bond in a covalent molecule is broken, resulting in gaseous fragments.

What characterizes a sigma (σ) bond?

A sigma bond forms when two orbitals overlap head-to-head, resulting in one region of overlap and allowing for rotation around the bond axis.

How does bond strength relate to bond length?

In general, shorter bonds are stronger, but a shorter bond does not necessarily mean it is stronger if the bond order is not considered.

What is a pi (π) bond?

A pi bond is formed when two p-orbitals overlap side-to-side, resulting in two regions of overlap and restricting rotation around the bond axis.

What is the bond order of a single bond?

The bond order of a single bond is 1, indicating one electron pair is shared between the atoms.

What are the characteristics of multiple bonds?

A double bond consists of one sigma bond and one pi bond; a triple bond consists of one sigma bond and two pi bonds.

Why is bond formation exothermic?

Formation of bonds from gaseous atoms is always exothermic because energy is released.

What is bond length?

The distance between the nuclei of the two atoms in a bond.

How does bond order relate to bond strength?

Higher bond order results in shorter and stronger bonds between the same two atoms.

What happens to potential energy as two hydrogen atoms approach each other?

Potential energy decreases as hydrogen atoms approach, and is most stable when energy is at a minimum.

What is the bond dissociation energy (BDE)?

The change of enthalpy when one mole of a bond in a covalent molecule is broken, resulting in gaseous fragments.

How does bond strength relate to bond length?

In general, shorter bonds are stronger, but a shorter bond does not necessarily mean it is stronger if the bond order is not considered.

What is the bond order of a single bond?

The bond order of a single bond is 1, indicating one electron pair is shared between the atoms.

What are the characteristics of multiple bonds?

A double bond consists of one sigma bond and one pi bond; a triple bond consists of one sigma bond and two pi bonds.

Why is bond formation exothermic?

Formation of bonds from gaseous atoms is always exothermic because energy is released.

What are the characteristics of a sigma ($\sigma$) bond?

• Formed by head-to-head overlap of atomic orbitals (s-s, s-p, or p-p).
  • Electron density is concentrated directly along the internuclear axis, forming one region of overlap.
  • Allows for free rotation around the bond axis.
  • Generally stronger than pi ($\pi$) bonds.

What are the characteristics of a pi ($\pi$) bond?

• Formed by side-to-side overlap of parallel p-orbitals.
  • Electron density is concentrated above and below the internuclear axis, forming two regions of overlap with a nodal plane along the internuclear axis.
  • Restricts rotation around the bond axis.
  • Generally weaker than sigma ($\sigma$) bonds.