Ch 5: Bonding and Intermolecular Forces Flashcards
Why aren’t electrons in d subshells considered valence electrons for transition metals?
Because valence electrons are in the highest n level, and the d subshell “goes back” one n level.
p. 90
The ideal Lewis structures satisfies the octet rule for all atoms and has a formal charge of zero on all the atoms.
If this is not possible then the best structure is the one that _________ the _________ of the formal charges.
minimizes
magnitudes
p. 92
For dot structures that must contain formal charges on one or more atoms, the best structures have ________ formal charges on the more ______________ element.
negative
electronegative
p. 92
When multiple dot structures seem possible, which atom should be chosen as the central atom?
the least electronegative atom
p. 93
Resonance structures are two or more structure where only _________ electrons, as well as ______ and ______ bonds may move around.
nonbonding
double
triple
p. 95
What is the one rule of VSEPR theory?
Since electrons repel one another, electron pairs, whether bonding or nonbonding, attempt to move as far apart as possible.
p. 99
What is bond dissociation energy?
the energy required to break a bond homolytically
p. 95
What does “homolytically” mean?
This refers to homolytic bond cleavage (or dissociation) where one electron of the bond being broken goes to each fragment of the molecule.
p. 95
Homolytic bond cleavage differs from HETEROLYTIC bond cleavage where both electrons of the bond being broken end up on the ____ ____, forming both a ______ and an _____.
same atom
cation, anion
p. 95
Hint: When you think of bond dissociation energy, think of a divorce in which each partner got an equal share of the assets. The “assets” in this case are _________.
electrons
The bond order is defined as…
…the number of bonds between adjacent atoms.
p. 95
The higher the bond order, the….
….shorter and stronger the bond.
p. 95
Bond lengths are often reported in angstrom. What is an angstrom?
What unit are bond dissociation energies given in?
10-10 m
kcal/mol
p. 95
Because of varying ______ _____, bond length and bond dissociation energy comparisons should be made for similar bonds (i.e. C-C bonds compared to other C-C bonds; C-O bonds compared to other C-O bonds)
atomic radii
p. 96
When comparing the same type of bonds, the greater the s character in the hybrid orbitals, the shorter the bond. Why is this?
because s-orbitals are closer to the nucleus than p-orbitals due to their shape. S-orbitals are spheres and p-orbitals have that dumbbell shape.
Example: an sp-sp bond will be shorter than an sp-sp3 bond
In other words, the fewer p’s involved, the shorter the bond will be.
p. 96
A sigma bond consists of 2 electrons that are _________ between 2 nuclei, formed by end-to-end overlap of orbitals from each of the 2 atoms participating in the bond.
localized
p. 104
A pi bond is composed of 2 electrons that are localized to the region that lies on each side of the plane formed by the ___ ______ ______ and immediately adjacent atoms, not directly between the two nuclei as with a sigma bond.
two bonded nuclei
In any multiple bond, there is only _ sigma bond, the remainder are __ bonds.
1
pi
p. 106
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX2E0
Bc there are no lone pairs, they will both have linear geometry. (bond angle 180 degrees)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX3E0
Bc there are no lone pairs, they will both have trigonal planar geometry. (bond angle 120 degrees)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX2E1
electron geometry will be trigonal planar, molecular geometry will be bent. (bond angle <120 degrees)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX4E0
Bc there are no lone pairs, they will both have tetrahedral geometry (bond angle 109.5)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX3E1
Electron geometry will be tetrahedral, molecular geometry will be trigonal pyramidal. (bond angle <109.5, ~107)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX2E2
Electron geometry will be tetrahedral, molecular geometry will be bent. (Bond angle will be < 109.5, ~105)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX5E0
Bc there are no lone pairs, they will both have trigonal bipyramidal geometry. (bond angles 90 and 120)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX4E1
Electron geometry will be trigonal bipyramidal, molecular geometry will be see-saw (bond angles <90, and <120)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX3E2
Electron geometry will be trigonal bipyramidal, molecular geometry will be a T-structure. (bond angle <90)
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX2E3
Electron geometry will be trigonal bipyramidal.
Molecular geometry will be linear. (Bond angle 180).
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX6E0
Bc there are no lone pairs, they will both have octahedral geometry. (Bond angles 90 and 90).
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX5E1
Electron geometry will be octahedral.
Molecular geometry will be square pyramidal. (Bond angles 90 and <90).
Name the electron and molecular geometry for a molecule with the following AXE classification:
AX4E2
Electron geometry will be octahedral.
Molecular geometry will be square planar. (Bond angles all 90).
