Molecular and Ionic Compound Structure and Properties

2.2 Intramolecular Force and Potential Energy

Essential Knowledge:

*These are taken directly from College Board

• A graph of potential energy versus the distance between atoms is a useful representation for describing the interactions between atoms. Such graphs illustrate both the equilibrium bond length (the separation between atoms at which the potential energy is lowest) and the bond energy (the energy required to separate the atoms) (SAP-3.B.1)  

• In a covalent bond, the bond length is influenced by both the size of the atom’s core and the bond order (i.e., single, double, triple). Bonds with a higher order are shorter and have larger bond energies. (SAP-3.B.2 ) 

• Coulomb’s law can be used to understand the strength of interactions between cations and anions. 

a. Because the interaction strength is proportional to the charge on each ion, larger charges lead to stronger interactions. 

b. Because the interaction strength increases as the distance between the centers of the ions (nuclei) decreases, smaller ions lead to stronger interactions (SAP-3.B.3 )