CEM 141 Exam 3 Questions and Answers Graded A+
change of state from solid -> liquid -> gas ________ energy - Answers requires
energy needed to phase change from solid --> liquid --> gas comes from: - Answers the
surroundings
when phases change from solid --> liquid --> gas, interactions are _______ between molecules -
Answers overcome
change of state from gas --> liquid --> solid ______ energy - Answers releases
what happens to the energy from a phase change from gas --> liquid --> solid? - Answers
released to surroundings
when phases change from gas --> liquid --> solid, interactions are _______ between molecules -
Answers formed
what happens when a substance melts? - Answers the interactions between the particles have
to be overcome -- so that they can remove relative to each other (that's what allows a liquid to
flow)
melting and boiling points provide an estimate of: - Answers the strength of the attractive
interactions between particles
which is stronger?? covalent bond/LDF - Answers covalent bond
in a covalent bond, what is formed? - Answers a new molecule
what is a LDF caused by? - Answers fluctuating charge distribution
covalent bonds are the sharing of: - Answers valence electrons
LDF's increase with.... - Answers the size of electron cloud
covalent bonds are caused by: - Answers attraction between electrons of one atom and the
nucleus of another
LDFs are present where??? - Answers between all molecular species
is it hard or easy to predict covalent bond strength? - Answers hard
when are covalent bonds present? - Answers when atomic orbitals interact constructively
covalent bonds are located: - Answers between molecules/networks
LDFs occur between: - Answers separate molecules
diamond has a high/low melting point??? - Answers high
, graphite has a high/low melting point?? - Answers high
diamond is hard/soft? - Answers hard
graphite is hard/soft? - Answers soft
diamond's physical properties - Answers brittle, translucent
diamond does/does not conduct electricity?? - Answers does not
graphite's physical properties - Answers slippery, shiny, grey
graphite does/does not conduct electricity? - Answers does
in diamond, each carbon forms how many bonds to how many carbons??? - Answers 4 bonds to
4 identical carbons
in diamond, the bonds between carbons arrange themselves towards: - Answers the corners of
a 4-sided figure (tetrahedron)
what is the C-C-C bond angle in diamond? - Answers 109°
what model of bonding is used to explain the bonding in carbon? - Answers Valence Bond
Theory
Valence Bond Theory - Answers atomic orbitals overlap to form bonds
how are bonds often shown in the valence bond theory? - Answers as "sticks"
in the Molecular Orbital Theory, atomic orbitals combine to form: - Answers an equal # of
molecular orbitals
in MO Theory, each orbital can contain up to ____ electrons - Answers 2
in MO theory, electrons in bonding orbitals (stabilized/destabilized) the system?? - Answers
stabilized
in MO theory, each bond is made up of how many electrons? - Answers 2 electrons
in MO theory, electrons are localized where? - Answers the bond
in the Valence Bond Theory, atomic orbitals _____ to form a bond - Answers overlap
in VB theory, the greater the overlap, the (weaker/stronger) the bond - Answers stronger
in VB theory, each bond is made up of how many electrons? - Answers 2 electrons
in VB theory, electrons are localized where? - Answers the bond
change of state from solid -> liquid -> gas ________ energy - Answers requires
energy needed to phase change from solid --> liquid --> gas comes from: - Answers the
surroundings
when phases change from solid --> liquid --> gas, interactions are _______ between molecules -
Answers overcome
change of state from gas --> liquid --> solid ______ energy - Answers releases
what happens to the energy from a phase change from gas --> liquid --> solid? - Answers
released to surroundings
when phases change from gas --> liquid --> solid, interactions are _______ between molecules -
Answers formed
what happens when a substance melts? - Answers the interactions between the particles have
to be overcome -- so that they can remove relative to each other (that's what allows a liquid to
flow)
melting and boiling points provide an estimate of: - Answers the strength of the attractive
interactions between particles
which is stronger?? covalent bond/LDF - Answers covalent bond
in a covalent bond, what is formed? - Answers a new molecule
what is a LDF caused by? - Answers fluctuating charge distribution
covalent bonds are the sharing of: - Answers valence electrons
LDF's increase with.... - Answers the size of electron cloud
covalent bonds are caused by: - Answers attraction between electrons of one atom and the
nucleus of another
LDFs are present where??? - Answers between all molecular species
is it hard or easy to predict covalent bond strength? - Answers hard
when are covalent bonds present? - Answers when atomic orbitals interact constructively
covalent bonds are located: - Answers between molecules/networks
LDFs occur between: - Answers separate molecules
diamond has a high/low melting point??? - Answers high
, graphite has a high/low melting point?? - Answers high
diamond is hard/soft? - Answers hard
graphite is hard/soft? - Answers soft
diamond's physical properties - Answers brittle, translucent
diamond does/does not conduct electricity?? - Answers does not
graphite's physical properties - Answers slippery, shiny, grey
graphite does/does not conduct electricity? - Answers does
in diamond, each carbon forms how many bonds to how many carbons??? - Answers 4 bonds to
4 identical carbons
in diamond, the bonds between carbons arrange themselves towards: - Answers the corners of
a 4-sided figure (tetrahedron)
what is the C-C-C bond angle in diamond? - Answers 109°
what model of bonding is used to explain the bonding in carbon? - Answers Valence Bond
Theory
Valence Bond Theory - Answers atomic orbitals overlap to form bonds
how are bonds often shown in the valence bond theory? - Answers as "sticks"
in the Molecular Orbital Theory, atomic orbitals combine to form: - Answers an equal # of
molecular orbitals
in MO Theory, each orbital can contain up to ____ electrons - Answers 2
in MO theory, electrons in bonding orbitals (stabilized/destabilized) the system?? - Answers
stabilized
in MO theory, each bond is made up of how many electrons? - Answers 2 electrons
in MO theory, electrons are localized where? - Answers the bond
in the Valence Bond Theory, atomic orbitals _____ to form a bond - Answers overlap
in VB theory, the greater the overlap, the (weaker/stronger) the bond - Answers stronger
in VB theory, each bond is made up of how many electrons? - Answers 2 electrons
in VB theory, electrons are localized where? - Answers the bond
