A scientist compares the bonding in three hypothetical diatomic molecules, X2, Y2
CHEMISTRY · Multi-part · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
A scientist compares the bonding in three hypothetical diatomic molecules, X2, Y2, and Z2.
• X2 contains a single covalent bond with a bond energy of 250 kJ mol⁻¹ and an equilibrium bond length of 150 pm.
• Y2 contains a double covalent bond between the same atoms found in X2.
• Z2 contains a triple covalent bond between the same atoms found in X2.
Answer the following questions about how the potential-energy curves of Y2 and Z2 would differ from that of X2.
(a) On appropriately labeled axes, sketch a single qualitative potential-energy curve for X2 (potential energy on the vertical axis, internuclear distance on the horizontal axis). Clearly label the equilibrium bond length and the bond energy on your sketch.
(b) On the same set of axes, sketch a second curve representing Y2. Describe how and why the position of its minimum and the depth of its well differ from those of X2.
(c) Still on the same axes, add a curve representing Z2. Describe how and why the position of its minimum and the depth of its well differ from those of both X2 and Y2.
(d) Identify the regions on any one of your curves where the net force between the nuclei is attractive and where it is repulsive, and explain the reasoning for each region in terms of potential-energy changes when the internuclear distance is altered.