CEM 141 EXAM 3 MSU
True. - ANS-T/F: Covalent bonds are present only when atomic orbitals interact constructively.
Each carbon forms 4 bonds to 4 identical carbons; tetrahedral; sp3 - ANS-Binding in Diamond
The idea that covalent bonds are formed when orbitals of different atoms overlap. -
ANS-Valence Bond Theory
False - ANS-T/F: Electrons are localized in molecular orbital.
True - ANS-T/F: Electrons are localized in Valence Bond.
True - ANS-T/F: When the hybrid orbitals combine, there is a large gap between the bonding
and anti bonding orbitals.
Sigma bonds. - ANS-Bonding in Tetrahedral C results in.....
3 sp2 orbitals; trigonal planar; sigma bond - ANS-Bonding in Graphite
Has a localized sigma bond network but has a delocalized pi network over the whole sheet of
atoms. - ANS-Is graphite localized ?
Higher boiling point and more surface area to overcome LDF's. - ANS-What does a larger
electron cloud provide?
No - bonds will break. - ANS-Can you rotate around a double bond?
Single covalent bond (sp2-sp2 overlap). - ANS-What is a sigma bond?
Sideways overlap of p orbitals that occur in a double or triple bond. - ANS-What is a Pi Bond?
Valence electrons - # of bonds - non bonded electrons - ANS-Formal Charge =
O: FC = 6 - 1 - 6 = -1. - ANS-Formal Charge on OH-?
Assume all centers of electrons density repel each other and that there is a minimum energy
arrangement that the atom will naturally take up. - ANS-Valence Shell Electron Pair Repulsion
(VSEPR)
True. - ANS-T/F: Multiple bonds count as one center of electron density in VSEPR.
, SP3. - ANS-What hybridization is tetrahedral?
True. - ANS-T/F: If there are no lone pairs on the central atom, the electron center geometry and
shape are the SAME.
Ability of an element to attract electrons to itself in a bond. - ANS-Electronegativity
Increase. - ANS-Does electronegativity increase or decrease across a period?
Decreases. - ANS-Does electronegativity increase or decrease down a group?
When 2 atoms of different electronegativities bond, the electrons are not shared equally (Dipole
= polar) - ANS-Polar Bonds
No. - ANS-Is a C-H bond polar?
Yes, must have magnitude and direction. - ANS-Are bond Dipoles vector quantities?
1. 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. - ANS-How to determine molecular polarity?
ONLY LDF'S. - ANS-What kind of intermolecular force is present in non-polar molecules?
-Present in polar substances (along with LDF)
-Typically stronger than LDF - ANS-Dipole-Dipole Interactions
True. - ANS-T/F: Polar molecules have stronger intermolecular interactions; therefore a higher
boiling & melting point.
Present between 2 molecules; first H bonded to O,N, or F; and the second bonded to O, N, or F
w/ a lone pair. - ANS-Hydrogen Bonding
Hydrogen, dipole-dipole, LDF's - ANS-What types of intermolecular forces exist in hydrogen
bonding?
1) Molecular Formula
2) Lewis Structure
3) Electron Pair Geometry
4) Molecular Shape
5) Identification of bond properties
True. - ANS-T/F: Covalent bonds are present only when atomic orbitals interact constructively.
Each carbon forms 4 bonds to 4 identical carbons; tetrahedral; sp3 - ANS-Binding in Diamond
The idea that covalent bonds are formed when orbitals of different atoms overlap. -
ANS-Valence Bond Theory
False - ANS-T/F: Electrons are localized in molecular orbital.
True - ANS-T/F: Electrons are localized in Valence Bond.
True - ANS-T/F: When the hybrid orbitals combine, there is a large gap between the bonding
and anti bonding orbitals.
Sigma bonds. - ANS-Bonding in Tetrahedral C results in.....
3 sp2 orbitals; trigonal planar; sigma bond - ANS-Bonding in Graphite
Has a localized sigma bond network but has a delocalized pi network over the whole sheet of
atoms. - ANS-Is graphite localized ?
Higher boiling point and more surface area to overcome LDF's. - ANS-What does a larger
electron cloud provide?
No - bonds will break. - ANS-Can you rotate around a double bond?
Single covalent bond (sp2-sp2 overlap). - ANS-What is a sigma bond?
Sideways overlap of p orbitals that occur in a double or triple bond. - ANS-What is a Pi Bond?
Valence electrons - # of bonds - non bonded electrons - ANS-Formal Charge =
O: FC = 6 - 1 - 6 = -1. - ANS-Formal Charge on OH-?
Assume all centers of electrons density repel each other and that there is a minimum energy
arrangement that the atom will naturally take up. - ANS-Valence Shell Electron Pair Repulsion
(VSEPR)
True. - ANS-T/F: Multiple bonds count as one center of electron density in VSEPR.
, SP3. - ANS-What hybridization is tetrahedral?
True. - ANS-T/F: If there are no lone pairs on the central atom, the electron center geometry and
shape are the SAME.
Ability of an element to attract electrons to itself in a bond. - ANS-Electronegativity
Increase. - ANS-Does electronegativity increase or decrease across a period?
Decreases. - ANS-Does electronegativity increase or decrease down a group?
When 2 atoms of different electronegativities bond, the electrons are not shared equally (Dipole
= polar) - ANS-Polar Bonds
No. - ANS-Is a C-H bond polar?
Yes, must have magnitude and direction. - ANS-Are bond Dipoles vector quantities?
1. 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. - ANS-How to determine molecular polarity?
ONLY LDF'S. - ANS-What kind of intermolecular force is present in non-polar molecules?
-Present in polar substances (along with LDF)
-Typically stronger than LDF - ANS-Dipole-Dipole Interactions
True. - ANS-T/F: Polar molecules have stronger intermolecular interactions; therefore a higher
boiling & melting point.
Present between 2 molecules; first H bonded to O,N, or F; and the second bonded to O, N, or F
w/ a lone pair. - ANS-Hydrogen Bonding
Hydrogen, dipole-dipole, LDF's - ANS-What types of intermolecular forces exist in hydrogen
bonding?
1) Molecular Formula
2) Lewis Structure
3) Electron Pair Geometry
4) Molecular Shape
5) Identification of bond properties
