CEM 141 EXAM 3 MSU EXAM
QUESTIONS AND ANSWERS 2026
T/F: Covalent bonds are present only when atomic orbitals interact constructively. -
ANSWERSTrue.
Binding in Diamond - ANSWERSEach carbon forms 4 bonds to 4 identical carbons;
tetrahedral; sp3
Valence Bond Theory - ANSWERSThe idea that covalent bonds are formed when
orbitals of different atoms overlap.
T/F: Electrons are localized in molecular orbital. - ANSWERSFalse
T/F: Electrons are localized in Valence Bond. - ANSWERSTrue
T/F: When the hybrid orbitals combine, there is a large gap between the bonding and
anti bonding orbitals. - ANSWERSTrue
Bonding in Tetrahedral C results in..... - ANSWERSSigma bonds.
Bonding in Graphite - ANSWERS3 sp2 orbitals; trigonal planar; sigma bond
Is graphite localized ? - ANSWERSHas a localized sigma bond network but has a
delocalized pi network over the whole sheet of atoms.
What does a larger electron cloud provide? - ANSWERSHigher boiling point and more
surface area to overcome LDF's.
Can you rotate around a double bond? - ANSWERSNo - bonds will break.
What is a sigma bond? - ANSWERSSingle covalent bond (sp2-sp2 overlap).
What is a Pi Bond? - ANSWERSSideways overlap of p orbitals that occur in a double or
triple bond.
Formal Charge = - ANSWERSValence electrons - # of bonds - non bonded electrons
Formal Charge on OH-? - ANSWERSO: FC = 6 - 1 - 6 = -1.
Valence Shell Electron Pair Repulsion (VSEPR) - ANSWERSAssume all centers of
electrons density repel each other and that there is a minimum energy arrangement that
the atom will naturally take up.
, T/F: Multiple bonds count as one center of electron density in VSEPR. -
ANSWERSTrue.
What hybridization is tetrahedral? - ANSWERSSP3.
T/F: If there are no lone pairs on the central atom, the electron center geometry and
shape are the SAME. - ANSWERSTrue.
Electronegativity - ANSWERSAbility of an element to attract electrons to itself in a bond.
Does electronegativity increase or decrease across a period? - ANSWERSIncrease.
Does electronegativity increase or decrease down a group? - ANSWERSDecreases.
Polar Bonds - ANSWERSWhen 2 atoms of different electronegativities bond, the
electrons are not shared equally (Dipole = polar)
Is a C-H bond polar? - ANSWERSNo.
Are bond Dipoles vector quantities? - ANSWERSYes, must have magnitude and
direction.
How to determine molecular polarity? - ANSWERS1. Draw Lewis Structure
2. Determine the electron pair geometry
3. Determine molecular shape
4. Determine the bond polarities
5. Add up the bond polarities
6. Figure out the molecular polarity.
What kind of intermolecular force is present in non-polar molecules? - ANSWERSONLY
LDF'S.
Dipole-Dipole Interactions - ANSWERS-Present in polar substances (along with LDF)
-Typically stronger than LDF
T/F: Polar molecules have stronger intermolecular interactions; therefore a higher
boiling & melting point. - ANSWERSTrue.
Hydrogen Bonding - ANSWERSPresent between 2 molecules; first H bonded to O,N, or
F; and the second bonded to O, N, or F w/ a lone pair.
What types of intermolecular forces exist in hydrogen bonding? - ANSWERSHydrogen,
dipole-dipole, LDF's
Structure Properties - ANSWERS1) Molecular Formula
QUESTIONS AND ANSWERS 2026
T/F: Covalent bonds are present only when atomic orbitals interact constructively. -
ANSWERSTrue.
Binding in Diamond - ANSWERSEach carbon forms 4 bonds to 4 identical carbons;
tetrahedral; sp3
Valence Bond Theory - ANSWERSThe idea that covalent bonds are formed when
orbitals of different atoms overlap.
T/F: Electrons are localized in molecular orbital. - ANSWERSFalse
T/F: Electrons are localized in Valence Bond. - ANSWERSTrue
T/F: When the hybrid orbitals combine, there is a large gap between the bonding and
anti bonding orbitals. - ANSWERSTrue
Bonding in Tetrahedral C results in..... - ANSWERSSigma bonds.
Bonding in Graphite - ANSWERS3 sp2 orbitals; trigonal planar; sigma bond
Is graphite localized ? - ANSWERSHas a localized sigma bond network but has a
delocalized pi network over the whole sheet of atoms.
What does a larger electron cloud provide? - ANSWERSHigher boiling point and more
surface area to overcome LDF's.
Can you rotate around a double bond? - ANSWERSNo - bonds will break.
What is a sigma bond? - ANSWERSSingle covalent bond (sp2-sp2 overlap).
What is a Pi Bond? - ANSWERSSideways overlap of p orbitals that occur in a double or
triple bond.
Formal Charge = - ANSWERSValence electrons - # of bonds - non bonded electrons
Formal Charge on OH-? - ANSWERSO: FC = 6 - 1 - 6 = -1.
Valence Shell Electron Pair Repulsion (VSEPR) - ANSWERSAssume all centers of
electrons density repel each other and that there is a minimum energy arrangement that
the atom will naturally take up.
, T/F: Multiple bonds count as one center of electron density in VSEPR. -
ANSWERSTrue.
What hybridization is tetrahedral? - ANSWERSSP3.
T/F: If there are no lone pairs on the central atom, the electron center geometry and
shape are the SAME. - ANSWERSTrue.
Electronegativity - ANSWERSAbility of an element to attract electrons to itself in a bond.
Does electronegativity increase or decrease across a period? - ANSWERSIncrease.
Does electronegativity increase or decrease down a group? - ANSWERSDecreases.
Polar Bonds - ANSWERSWhen 2 atoms of different electronegativities bond, the
electrons are not shared equally (Dipole = polar)
Is a C-H bond polar? - ANSWERSNo.
Are bond Dipoles vector quantities? - ANSWERSYes, must have magnitude and
direction.
How to determine molecular polarity? - ANSWERS1. Draw Lewis Structure
2. Determine the electron pair geometry
3. Determine molecular shape
4. Determine the bond polarities
5. Add up the bond polarities
6. Figure out the molecular polarity.
What kind of intermolecular force is present in non-polar molecules? - ANSWERSONLY
LDF'S.
Dipole-Dipole Interactions - ANSWERS-Present in polar substances (along with LDF)
-Typically stronger than LDF
T/F: Polar molecules have stronger intermolecular interactions; therefore a higher
boiling & melting point. - ANSWERSTrue.
Hydrogen Bonding - ANSWERSPresent between 2 molecules; first H bonded to O,N, or
F; and the second bonded to O, N, or F w/ a lone pair.
What types of intermolecular forces exist in hydrogen bonding? - ANSWERSHydrogen,
dipole-dipole, LDF's
Structure Properties - ANSWERS1) Molecular Formula
