CEM 141 MODULE 2 TEST QUESTIONS
AND ANSWERS
What information does the depth of the potential well tell you about the strength of the
interaction? - Answer-The deeper the potential well, the more energy would be required
to get the atoms to separate. Therefore, the deeper the well, the stronger the
interaction.
What information can you get from the position of the potential minimum along the x-
axis (the distance between the atomic nuclei)? - Answer-You can determine the
distance between the nuclei when the atoms are most stable.
Describe the forces that are present and their respective strengths at the potential
minimum. - Answer-At the potential minimum the strength of the attractive forces equals
the strength of the repulsive forces. This allows a stable interaction to occur.
What happens as two Neon atoms approach each other? Use this explanation to help
explain why the two atoms are attracted to each other. - Answer-2 Nonpolar Ne atoms
as the Neon atoms get very close together their electron clouds overlap. Draw a picture
and use it to help you explain why the potential energy increases as the atoms get very
close. - Answer-As the atoms get very close, their electron clouds are essentially in the
same space.
The electrostatic repulsion between the electrons means that the atoms are forced
apart. Since energy had to be used to "push" the electrons together (in the form of
kinetic energy) this energy must be stored in the electrostatic field as potential
energy.
Draw a graph showing how the potential energy changes as the atoms move from far
apart to where they are smooshed together (a technical term!). - Answer-
Now draw a PE curve for the interaction of two Ne atoms, and then on the same set of
axes draw a curve for the interaction of two Xe atoms. Explain the relative depths of the
potential wells and the relative positions of the minima along the x-axis. - Answer-The
potential energy well is deeper for Xe because Xe has more electrons and
therefore has stronger LDFs.
The potential well for Xe has a longer distance between the nuclei than Ne because Xe
is a bigger atom (more electrons and larger electron cloud).
AND ANSWERS
What information does the depth of the potential well tell you about the strength of the
interaction? - Answer-The deeper the potential well, the more energy would be required
to get the atoms to separate. Therefore, the deeper the well, the stronger the
interaction.
What information can you get from the position of the potential minimum along the x-
axis (the distance between the atomic nuclei)? - Answer-You can determine the
distance between the nuclei when the atoms are most stable.
Describe the forces that are present and their respective strengths at the potential
minimum. - Answer-At the potential minimum the strength of the attractive forces equals
the strength of the repulsive forces. This allows a stable interaction to occur.
What happens as two Neon atoms approach each other? Use this explanation to help
explain why the two atoms are attracted to each other. - Answer-2 Nonpolar Ne atoms
as the Neon atoms get very close together their electron clouds overlap. Draw a picture
and use it to help you explain why the potential energy increases as the atoms get very
close. - Answer-As the atoms get very close, their electron clouds are essentially in the
same space.
The electrostatic repulsion between the electrons means that the atoms are forced
apart. Since energy had to be used to "push" the electrons together (in the form of
kinetic energy) this energy must be stored in the electrostatic field as potential
energy.
Draw a graph showing how the potential energy changes as the atoms move from far
apart to where they are smooshed together (a technical term!). - Answer-
Now draw a PE curve for the interaction of two Ne atoms, and then on the same set of
axes draw a curve for the interaction of two Xe atoms. Explain the relative depths of the
potential wells and the relative positions of the minima along the x-axis. - Answer-The
potential energy well is deeper for Xe because Xe has more electrons and
therefore has stronger LDFs.
The potential well for Xe has a longer distance between the nuclei than Ne because Xe
is a bigger atom (more electrons and larger electron cloud).
