Intramolecular Force & Potential Energy (College Board AP® Chemistry): Revision Note

A potential energy diagram represents the potential energy as a function of internuclear distance

• The distance at which the potential energy is at a minimum is the bond length of the covalent bond

• The difference between the minimum potential energy and zero is the bond energy, the amount of energy required to break the covalent bond

When two atoms are far away

• There is little attraction between the positively charged nucleus of one atom and the negatively charged electrons of the other atom

• The potential energy is near zero

When two atoms are very close

• The two positively charged nuclei and the two negatively charged electron clouds strongly repel one another

• The potential energy is very high

When two atoms form a stable covalent bond

• The attractive and repulsive forces between the two atoms are balanced

• The potential energy is at a minimum

As atomic radius increases, bond length increases

• Bond length is typically reported in units of picometers (pm)

• A picometer is 1 × 10^-12 m

Bond order indicates the number of electron pairs that are shared between two atoms

As bond order increases, bond length decreases while bond energy increases