KEY2CHEM

Potential Energy

Potential energy is the energy related to the position of the system. In terms of interactions between particles, the closer the particles are, the more strongly attracted they are to one another. This can be related back to Coulomb’s law ($$F \propto \frac{q_1 \times q_2}{r^2}$$). As the electrostatic charge on the separated particles increases in magnitude (opposite in charge) and the distance separating the particles decreases, the attractive interaction between the particles increases.

Example 1.

Which particles will be most strongly attracted to one another?

A.

B.

C.

Solution

A.

As the distance separating particles decreases, their attraction increases.

Example 2.

Which compound is expected to have the strongest interparticle forces?

A. $$\require{mhchem}\ce{CH4}$$

B. $$\require{mhchem}\ce{H2S}$$

C. $$\require{mhchem}\ce{H2O}$$

Solution

C. $$\require{mhchem}\ce{H2O}$$

The electrostatic attraction between water molecules (greatest difference in electronegativity between the atoms) creates the strongest interparticle forces.

Example 3.

Which bond is expected to be the strongest?

A. $$\require{mhchem}\ce{C-C}$$

B. $$\require{mhchem}\ce{C=C}$$

C. $$\require{mhchem}\ce{C#C}$$

Solution

C. $$\require{mhchem}\ce{C#C}$$

The triple bond (Bond order of $$3$$) is the strongest bond; the atoms are held together by three pairs of electrons. The length of the triple bond is shorter than the double bond or the single bond.