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