CHEM 141 Exam 3 2025 Questions and
Answers
Differentiate between properties of atoms, nano-particles, and larger
macroscale materials. Explain why is it that atoms don't have macroscopic
properties like melting point, boiling point, and color, while macroscopic materials
do (and can be identified by them). - --CORRECT ANSWER--The properties of
new substances depend on its molecular structure - the properties are emergent
For molecules to melt they interact with other molecules. It would not be possible
to melt a single atom/molecule.
Explain the force and energy changes that occur when two atoms approach each
other and form a bond. Explain why a third body (another atom or molecule) is
(almost always) needed to form a stable bond. (Think back to what we learned in
Chapter 1. - --CORRECT ANSWER--A third atom will absorb some of the energy
thus lowering the energy between to atoms allowing the two atoms to form a
stable bond.
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, What determines whether a bond or interaction is stable? Explain how temperature
influences the stability of bonds and interactions - --CORRECT ANSWER--The
stability of atoms depends on whether or not their outer-most shell is filled with
electrons. If the outer shell is filled, the atom is stable.
If you put enough energy (heat/temperature) in, the bond will break and the atoms
connected by that bond will fly apart.
Compare and contrast the molecular orbital bond model and the valence bond
model. What are the similarities? What are the differences - --CORRECT
ANSWER--...
Valence Bond Theory - --CORRECT ANSWER--two orbitals combine to form a
bond between two atoms
a single pair of electrons can be shared only by two, bonded atoms in the molecule
focuses on bonding interactions
uses hybridization to explain geometry of molecules
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
Answers
Differentiate between properties of atoms, nano-particles, and larger
macroscale materials. Explain why is it that atoms don't have macroscopic
properties like melting point, boiling point, and color, while macroscopic materials
do (and can be identified by them). - --CORRECT ANSWER--The properties of
new substances depend on its molecular structure - the properties are emergent
For molecules to melt they interact with other molecules. It would not be possible
to melt a single atom/molecule.
Explain the force and energy changes that occur when two atoms approach each
other and form a bond. Explain why a third body (another atom or molecule) is
(almost always) needed to form a stable bond. (Think back to what we learned in
Chapter 1. - --CORRECT ANSWER--A third atom will absorb some of the energy
thus lowering the energy between to atoms allowing the two atoms to form a
stable bond.
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
, What determines whether a bond or interaction is stable? Explain how temperature
influences the stability of bonds and interactions - --CORRECT ANSWER--The
stability of atoms depends on whether or not their outer-most shell is filled with
electrons. If the outer shell is filled, the atom is stable.
If you put enough energy (heat/temperature) in, the bond will break and the atoms
connected by that bond will fly apart.
Compare and contrast the molecular orbital bond model and the valence bond
model. What are the similarities? What are the differences - --CORRECT
ANSWER--...
Valence Bond Theory - --CORRECT ANSWER--two orbitals combine to form a
bond between two atoms
a single pair of electrons can be shared only by two, bonded atoms in the molecule
focuses on bonding interactions
uses hybridization to explain geometry of molecules
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
