Chemistry 1210 chapter 9 (final) notes homework quiz
molecular
Combining two atomic orbitals on two different atoms forms a molecular or hybrid orbital
No. All four hybrids are equivalent and the angles between them are all the same, so we can use any of the two to hold the nonbonding pairs.
Does it matter which of the two sp3 hybrid orbitals are used to hold the two nonbonding electron pairs?
2
If the valence atomic orbitals of an atom are sp hybridized, how many unhybridized p orbitals remain in the valence shell? Express your answer as an integer.
It would be easier to twist around a single σ bond.
Imagine that you could hold two atoms that are bonded together, twist them, and not change the bond length. Would it be easier to twist (rotate) around a single σ bond or around a double (σ plus π) bond, or would they be the same?
decreases
Supposing the A−X bond is polar, how would you expect the dipole moment of the AX3 molecule to change as the X−A−X bond angle increases from 100∘ to 120∘?
true
T or F: Antibonding orbitals are higher in energy than bonding orbitals (if all orbitals are created from the same atomic orbitals).
false
T or F: Electrons cannot occupy an antibonding orbital.
false
T or F: Nonbonding electron pairs cannot occupy a hybrid orbital.
true
T or F: The greater the orbital overlap in a bond, the shorter the bond.
false
T or F: The greater the orbital overlap in a bond, the weaker the bond.
false
T or F: The probability is 100% for finding an electron at the nucleus in a π∗ orbital.
false
T or F: To create a hybrid orbital, you could use the s orbital on one atom with a p orbital on another atom.
true
T or F: electron domains for multiple bonds exert a greater repulsive force on adjacent electron domains than do electron domains for single bonds
true
T or F: s orbitals can make only σ or σ∗ molecular orbitals.
120
What is the angle formed between the large lobes of the three sp2 hybrid orbitals?
Both p orbitals are perpendicular to the F−Be−F bond axes.
What is the orientation of the two unhybridized p orbitals on Be with respect to the two Be−F bonds?
hypervalent
a compound with more than an octet of electrons around the central atom
pi bond
a covalent bond in which electron density is concentrated above and below the internuclear axis, produced by the sideways overlap of p orbitals (double or triple bond)
sigma bond
a covalent bond in which electron density is concentrated along the internuclear axis (single bonds)
sp hybridization
a linear arrangement of electron domains implies what type of hybridization
valence-bond theory
a model of chemical bonding in which an electron pair bond is formed between 2 atoms by the overlap of orbitals on the 2 atoms
sigma molecular orbitals
a molecular orbital that centers the electron density about an imaginary line passing through two nuclei
pi molecular orbital
a molecular orbital that concentrates the electron density on opposite sides of an imaginary line that passes through the nuclei
diamagnetism
a type of magnetism that causes a substance with no unpaired electrons to be weakly repelled from a magnetic field
VSEPR Model (Valence Shell Electron Pair Repulsion)
accounts for geometric arrangements of shared and unshared electron pairs around a central atom in terms of the repulsions between electron pairs
molecular orbital theory
accounts for the allowed states for electrons in molecules by using specific wave functions
molecular orbital
an allowed state for an electron in a molecule
hybrid orbitals
an orbital that results from the mixing of different kinds of atomic orbitals on the same atom
bond dipole
asymmetric charge distribution between two bonded atoms with unequal electronegativities
1/2(bonding electrons-antibonding electrons)
bond order equation
destructive combination
combining the two atomic orbitals in a way that causes the electron density to be canceled in the central region where the two overlap
hybrid
combining two atomic orbitals on a single atom forms a molecular or hybrid orbital
homonuclear diatomic orbitals
composed of 2 identical atoms
do not
core electrons usually do or do not contribute significantly to bonding in molecules
energy-level diagram/ MO diagram
diagram that shows the energies of molecular orbitals relative to the atomic orbitals from which they are derived
antibonding molecular orbital
electron density is concentrated outside the region between the 2 nuclei of bonded atoms (sigma star or pi star) are less stable (higher energy) than bonding molecular orbitals
delocalized
electrons that are spread over a number of atoms in a molecule or a crystal rather than localized on a single atom or a pair of atoms
nodal plane
in an antibonding orbital, the plane in the region between the nuclei where the electron density is zero
bonding pair
in lewis structure, pair of electrons that is shared by two atoms
electron domain
in the VSEPR model, a region about a central atom in which an electron pair is concentrated
polar
is IF polar or nonpolar?
nonpolar
is XeF4 polar or nonpolar?
no unless it is diatomic
is bond dipole a measurable physical property
yes
is molecular dipole moment a measurable physical property
nonbonding pair/ lone pair
lewis structure a pair of electrons assigned completely to one atom
more
the greater the electronegativity, the more or less the nonbonding electrons will be attracted to the atom
hybridization
the mathematical mixing of different types of atomic orbitals to produce a set of equivalent hybrid orbitals
when they are on the central atom of the lewis structure
the only time nonbonding electron pairs affect molecular shape is
increases up and to the right
trend for electronegativity
constructive combination
whenever 2 atomic orbitals overlap, 2 molecular orbitals form
molecular geometry
the arrangement in space of the atoms of a molecule- involves only electron domains due to bonds
minimizes the repulsions among them
the best arrangement of a given number of electron domains is the one that
the polarities of the individual bonds and the geometry of the molecule
the dipole moment depends on both
bond dipole
the dipole moment that is due only to unequal electron sharing between 2 atoms in a covalent bond
bonding molecular orbital
the electron density is concentrated in the internuclear region. the energy of a bonding molecular orbital is lower than the energy of the separate atomic orbitals from which it forms
molecular dipole moment
3D sum of all the bond dipoles in a molecule
paramagnetism
A property that a substance possesses if it contains one or more unpaired electrons. it is drawn into a magnetic field.
1. number of MOs formed equals number of atomic orbitals combined 2. atomic orbitals combine most effectively with other atomic orbitals of similar energy 3. the effectiveness with which 2 atomic orbitals combine is proportional to their overlap. as the overlap increases, energy of the bonding MO is lowered and the energy of the antibonding MO is raised 4. each MO can accommodate, at most, 2 electrons with their spins paired (pauli exclusion principle) 5. when MOs of the same energy are populated, one electron enters each orbital (with same spin) before spin pairing occurs (hund's rule)
period 2 MO rules
weaker
pi bonds generally stronger or weaker than sigma bonds?
electron-domain geometry
the 3D arrangement of the electron domains surrounding central atom