CHEM 1035 - SmartBook Chapter 10 Part II

The Lewis structure for the cyanide ion is shown. The formal charge on the C atom is equal to _____ and the formal charge on the N atom is equal to _____. Multiple choice question. +1; 0 -1; 0 0; +1 0; -1

-1; 0

Certain molecules are electron deficient, having fewer than __________ electrons around the central atom, which nonetheless has a formal charge of zero. Elements that commonly form electron deficient gaseous compounds are beryllium and __________.

8 boron

Which of the following is the correct Lewis structure for the cation ICl2+? Multiple choice question. A B C D

A

Arrange the following resonance forms in order of increasing importance in terms of their contribution to the overall structure, starting with the least important form at the top of the list. Electronegativities of the elements are as follows: C = 2.5; S = 2.5; N = 3.0 A B C

A C B

Which of the following structures ARE valid resonance forms for the molecule sulfur dioxide (SO2)? Select all that apply. Note that formal charges have not been included in the given structures. Multiple select question. A B C D

A D

Which of the following structures are NOT valid resonance forms for the sulfite ion, SO32-? Select all that apply. Multiple select question. A B C D

B C

The formal charge of an atom in a Lewis structure is the charge the atom would have if all bonding electrons were shared __________ between the atoms. The formal charge does not necessarily reflect an actual charge on the atom.

equally

Some elements do not obey the octet rule because they have more than eight valence electrons, i.e., they have a(n) __________ valence shell. This is only possible for elements that have available __________ orbitals, i.e., elements from period __________ of the periodic table onward.

expanded d 3

To show the bonding in a molecule or polyatomic ion, we can use a Lewis structure, which shows bonding electron pairs as ______ and any nonbonding electrons as ______. Multiple choice question. lines; lines lines; dots dots; lines

lines; dots

In a Lewis structure, _______. (Select all that apply.) Multiple select question. all electrons for each atom are included lone pairs are shown as pairs of dots bonding electron pairs are shown as lines nonbonding electrons are omitted atom symbols are omitted

lone pairs are shown as pairs of dots bonding electron pairs are shown as lines

Some covalently bonded species do not obey the octet rule because they have an odd number of electrons. A species containing one or more _____ electrons is called a free radical. Most odd-electron molecules have a central atom from an odd-numbered group, either Group _____ or Group _____. Multiple choice question. unpaired; 3A; 5A lone pair; 5A; 7A lone pair; 3A; 5A unpaired; 5A; 7A

unpaired; 5A; 7A

The formal charge assigned to an atom is calculated by subtracting the number of __________ electrons the atom "owns" from the total number of electrons. The number of electrons owned by a specific atom is defined as being the sum of the __________ valence electrons and half the __________ valence electrons.

valence unbonded bonded

Which of the following statements correctly describe the relative stabilities of resonance forms? Select all that apply. Multiple select question. A resonance structure with like charges on adjacent atoms is more stable than one with opposite charges on adjacent atoms. A resonance structure with formal charges closer to zero on individual atoms is preferred. A resonance structure with multiple bonds is always preferred to a resonance structure with only single bonds. A resonance structure is more stable if a negative charge resides on a more electronegative atom.

A resonance structure with formal charges closer to zero on individual atoms is preferred. A resonance structure is more stable if a negative charge resides on a more electronegative atom.

Select the statements that correctly describe the limitations of Lewis structures and formal charges. Multiple select question. A single Lewis structure often cannot correctly represent a molecule. Lewis structures are much more simplistic than actual structures. Formal charge rules sometimes do not choose the Lewis structure arrived at by quantum mechanics calculations. Formal charge rules often do not choose the Lewis structure consistent with experimental data.

A single Lewis structure often cannot correctly represent a molecule. Formal charge rules sometimes do not choose the Lewis structure arrived at by quantum mechanics calculations.

Which of the following statements correctly describe resonance structures? Select all that apply. Multiple select question. An individual resonance structure does not accurately represent the structure of the species. Resonance structures are isomers of the same species. Resonance structures differ only in the arrangement of electrons. Resonance forms rapidly interconvert. The species could have any one of these structures at any time.

An individual resonance structure does not accurately represent the structure of the species. Resonance structures differ only in the arrangement of electrons.

Which of the following elements, when covalently bonded, commonly have fewer than an octet of electrons with a formal charge of zero? Select all that apply. Multiple select question. Boron Phosphorus Silicon Chlorine Beryllium

Boron Beryllium

Which of the following Lewis structures gives the best representation for the molecule NO? Multiple choice question. A Reason: Although A is one possible resonance structure for NO, the less electronegative atom (N) has the negative formal charge. A is a minor contributor. B Reason: B has only 9 valence electrons instead of 11. C Reason: Correct. C is the major resonance contributor for NO.

C

True or false: Resonance structures are different possible structures for the same species that interconvert rapidly. True false question. True False

False

Which of the following are odd-electron species? Select all that apply. Multiple select question. ClO ClO2- N2O NO2

ClO NO2

The nitrite ion, NO2-, is a resonance hybrid and has two resonance forms, as shown. Select all the statements that correctly describe the bonding in this species. Multiple select question. The N=O bond in this ion is shorter than the N-O bond. Each N-O bond is a partial double bond. The NO2- ion can have either of these two structures at any one time. The bond order for this species is 1.5. Two electron pairs are delocalized over the entire species.

Each N-O bond is a partial double bond. The bond order for this species is 1.5. Two electron pairs are delocalized over the entire species.

Which of the following options correctly defines resonance structures? Multiple choice question. Lewis structures for the same species that differ in the placement of electrons Lewis structures that contain multiple bonds Lewis structures for the same species that have a different total number of electrons Lewis structures that have the same molecular formula but a different placement of atoms

Lewis structures for the same species that differ in the placement of electrons

Which of the following statements correctly describe resonance structures? Select all that apply. Multiple select question. Resonance structures differ only in the arrangement of electrons. Resonance forms rapidly interconvert. The species could have any one of these structures at any time. Resonance structures are isomers of the same species. An individual resonance structure does not accurately represent the structure of the species.

Resonance structures differ only in the arrangement of electrons. An individual resonance structure does not accurately represent the structure of the species.

Which of the following elements may have an expanded valence shell? Select all that apply. Multiple select question. S O Cl Xe N

S Cl Xe

Consider the Lewis structures shown for the species SOCl2. Not all are possible resonance forms, and formal charges have been deliberately omitted from individual atoms. Select all the statements that correctly describe the structure of SOCl2. Multiple select question. Structure C is preferred because O can use an expanded valence shell to minimize the formal charges. Structure D is preferred because both S and Cl can use an expanded valence shell. Structure B is preferred because all formal charges are zero. Structure A is preferred because all atoms have a full octet. S can use an expanded valence shell because it has available d orbitals.

Structure B is preferred because all formal charges are zero. S can use an expanded valence shell because it has available d orbitals.

Which of the following statements correctly describe how formal charge is assigned to an atom in a Lewis structure? Select all that apply. Multiple select question. The atom is considered to own half the shared electrons. The number of shared electrons equals twice the number of bonds in the structure. Formal charge = (unshared e- + 1212shared e-) - (valence e-) Formal charge = (valence e-) - (unshared e- + 1212shared e-) The atom is considered to own half the unshared electrons.

The atom is considered to own half the shared electrons. The number of shared electrons equals twice the number of bonds in the structure. Formal charge = (valence e-) - (unshared e- + 1212shared e-)

Which of the following statements correctly describe formal charge? Select all that apply. Multiple select question. The formal charge of an atom is the charge it would have if all bonding electrons were shared equally. The formal charge of an atom reflects the number of electrons the atom has lost or gained to form a bond. The formal charges of the atoms in a species must add up to zero. Formal charges can be used to select the most important resonance structures for a species.

The formal charge of an atom is the charge it would have if all bonding electrons were shared equally. Formal charges can be used to select the most important resonance structures for a species.

Draw two Lewis structures (one of which contains only single bonds) for the phosphate ion, PO43-. Which is the more important structure according to formal charge rules? Multiple choice question. The more important structure contains a double bond, resulting in a formal charge of zero on P, -1 on the doubly bonded O, and 0 on other O atoms. The more important structure contains all single bonds, resulting in a formal charge of 0 on P, and -1 on the O atoms. The more important structure contains a double bond, resulting in a formal charge of zero on P, 0 on the doubly bonded O, and -1 on other O atoms. The more important structure contains all single bonds, resulting in a formal charge of +1 on P, and -1 on the O atoms.

The more important structure contains a double bond, resulting in a formal charge of zero on P, 0 on the doubly bonded O, and -1 on other O atoms.

Which of the following statements correctly describe limitations to the use of formal charges when selecting Lewis structures of species with exceptions to the octet rule? Select all that apply. Multiple select question. The rules do not always select the most important resonance structure for species with unpaired electrons (free radicals). The rules do not always select the same structure as that calculated by quantum mechanics. The rules do not always select the experimentally accurate structures for species with expanded valence shells. The rules do not apply to species with electron-deficient central atoms. The rules do not allow for more than two resonance structures for a species.

The rules do not always select the most important resonance structure for species with unpaired electrons (free radicals). The rules do not always select the same structure as that calculated by quantum mechanics. The rules do not always select the experimentally accurate structures for species with expanded valence shells.

A given species has a bond order of 1 1/2. What does this fractional bond order indicate? Select all that apply. Multiple select question. The species contains delocalized electrons. The species is not very stable. The species cannot exist. The species is a resonance hybrid.

The species contains delocalized electrons. The species is a resonance hybrid.

A species that contains a lone (unpaired) electron is referred to as ______. Select the best answer. Multiple choice question. being electron deficient an exception a free radical having an extended valence

a free radical

Calculate the formal charges on each of the nitrogen atoms in the N3- ion shown. The overall charge of the ion has been omitted in the structure. Multiple choice question. a = -1; b = +1; c = -1 a = 0; b = +1; c = -1 a = -1; b = 0; c = +1 a = +1; b = -1; c = +1

a = -1; b = +1; c = -1

Resonance structures are Lewis structures that have the same relative placement of _____ but a different arrangement of _____. Multiple choice question. electrons; bonds bonding electrons; lone pair electrons electrons; atoms atoms; electrons

atoms; electrons

Partial bonding, for example, as part of a resonance hybrid, often results in structures with _____. Multiple choice question. negative bond orders fractional bond orders bond orders of two bond orders of zero bond orders of one

fractional bond orders

A species that contains a lone (unpaired) electron is called a __________ __________. These paramagnetic species are extremely reactive.

free radical

A resonance structure with more charges will be __________ stable than a resonance structure with fewer charges. For two resonance forms with the same formal charges, the resonance structure that has the negative formal charge on the more __________ atom will be more stable.

less electronegative

Use formal charges to determine which of the two resonance forms shown is more stable. B -> a ->

less stable more stable

In a single, double, or triple bond, the shared electron pairs are localized between the bonded atoms. In a resonance hybrid, electrons are _________ or spread out over two or more adjacent atoms. Instead of a double or triple bond between two such atoms, the bond is considered a(n) __________ double or triple bond with a fractional bond order.

shared partial