Ch 11

Which of the following options correctly describe σ and π molecular orbitals? Select all that apply. Multiple select question.

A π bonding molecular orbital has two regions of high electron density. Both atomic s and p orbitals can form σ molecular orbitals. Atomic p orbitals can combine to form either σ or π molecular orbitals.

Valence bond theory describes a single covalent bond as the _____ of orbitals from two atoms to form a shared space, which is occupied by _____ electron(s).

Overlap;two

Pi bond

Restricts Rotation

σ2p

Single region of high electron density between bonded nuclei

Consider the combination of two atomic orbitals to form a pair of molecular orbitals, designated σ2s and σ∗2sσ2s*. Which of the following statements explain these designations correctly? Select all that apply.

The atomic orbitals that combine in this case are s orbitals. Both orbitals are designated σ because they are cylindrically symmetrical.

π2p

Two separate regions of high electron density between nuclei, above and below bond axis

A double bond is ______ a single bond because the strength of the π bond component is ______ that of the σ bond component. Multiple choice question.

less than twice as strong as; weaker than

A π bond is ______ than a σ bond because it involves a _____ degree of orbital overlap.

weaker; lesser

Which of the following statements correctly describe the formation of sp2 hybrid orbitals? Select all that apply.

A group of sp2 hybrid orbitals assumes a trigonal planar geometry. The formation of sp2 hybrid orbitals leaves one unhybridized valence p orbital.

MO theory replaces resonance structures associated with ______ electrons assigned to individual bonds with extended areas of electron density associated with ______ electrons in bonding MOs over the entire molecule.

Localized; Delocalized

Each sp hybrid orbital has one large and one small lobe. The energy of an sp hybrid orbital lies between the energies of the original s and p orbital that were mixed.

Which of the following options correctly describe sp hybrid orbitals? Select all that apply.

σ∗2pσ2p* and π2π2

Zero electron density between bonded nuclei

Which of the following statements correctly describe the general principles of molecular orbital theory? Select all that apply.

Bonding involves the addition and subtraction of wave functions. Orbitals are viewed as wave functions. The addition of two wave functions produces a region with increased electron density.

The molecular orbital bond order is calculated as 1212[x - y] where x is the number of electrons in _____ molecular orbitals and y is the number of electrons in _____ molecular orbitals. In general, the higher the molecular orbital bond order, the _____ the bond strength for the species. Multiple choice question.

Bonding; antibonding; Greater

Which of the following statements correctly describe the rules used for placing electrons in molecular orbitals? Select all that apply. (MO is an abbreviation for molecular orbital.) Multiple select question.

Orbitals are filled in order of increasing energy. If two MOs have equal energy, an electron must be placed in each orbital before pairing up. Lower energy orbitals are filled before placing electrons in higher energy orbitals.

Which of the following options correctly describe a molecular orbital (MO) energy-level diagram? Select all that apply.

The MO diagram can be used to calculate bond order and predict the stability of a species. The MO diagram shows the relative energy and number of electrons in each MO. The MO diagram typically includes valence-shell molecular orbitals only.

A particular hybrid orbital is designated sp3d2. What information is provided by the superscripts in this designation? Multiple choice question.

The number of each type of atomic orbital combined to produce this type of hybrid orbital

Which of the following statements correctly describe bonding and antibonding molecular orbitals? Select all that apply.

A bonding molecular orbital is formed by the addition of the wave functions for two atomic orbitals. An antibonding molecular orbital has a region of zero electron density between the nuclei of the bonding atoms. A bonding molecular orbital is lower in energy than the original atomic orbitals.

Which of the following statements correctly describe a π bond? Select all that apply. Multiple select question.

A multiple bond always contains at least one π bond. A π bond is formed by the side-to-side overlap of two p orbitals.

Which of the following statements correctly describe molecular orbital bond orders? Select all that apply. Multiple select question.

A species with more electrons in bonding than antibonding molecular orbitals will have a positive molecular orbital bond order. The lower the molecular orbital bond order, the weaker the bonds between the atoms of the species.

Which of the following statements correctly describe a σ bond? Select all that apply. Multiple select question.

A σ bond results from end-to-end overlap of two orbitals. Single bonds are σ bonds.

Sigma bond

Almost Free Rotation

Which of the following statements correctly describe sp3 hybrid orbitals? Select all that apply.

An sp3 hybrid orbital is unsymmetrical in shape, having one small and one large lobe. The four sp3 hybrid orbitals of a group are equivalent in shape and energy.

Which of the following steps are necessary to determine the hybridization of the central atom? Select all that apply. Multiple select question.

Deduce the hybridization of the central atom based on the geometry of the molecule. Predict the geometry of the molecule using the VSEPR model. Draw the Lewis structure of the molecule.

A molecular orbital is a region of space in a covalent species where electrons are likely to be found. The combination of two atomic orbitals always forms two molecular orbitals; the bonding molecular orbital, which is _____ in energy, and the antibonding molecular orbital, which is _____ in energy, than the original atomic orbitals.

Lower; Higher

Which of the following statements correctly describe a covalent bond in terms of valence bond theory? Select all that apply.

The electrons of a shared pair must have opposite spins. A covalent bond is formed by the overlap of an orbital from each of the bonding atoms. The greater the overlapped area, the stronger the bond.

The lower the molecular orbital bond order, the _____ the bond and the _____ stable the species.

Weaker; less