Chem 6.1 - 6.5

The covalently bonded species shown has _____ bonding pair(s) of electrons and _____ lone pair(s). 4; 0 3; 1 2; 2 1; 3

3; 1

Select all the statements that correctly describe how to draw a Lewis structure. Nonbonded electrons do not need to be included in the structure. A Lewis structure includes all the valence electrons in the species. An electron is added to the total count for each negative charge on the species. A single bond contains 2 electrons and is represented by a solid line. The atom with the highest group number is usually placed in the center of the structure.

A Lewis structure includes all the valence electrons in the species. An electron is added to the total count for each negative charge on the species. A single bond contains 2 electrons and is represented by a solid line.

Which of the following statements about Lewis structures are correct? A covalent bond is represented as a line or as dots between atoms. A Lewis structure shows the number of covalent bonds between bonded atoms. Lone pair electrons are represented as pairs of dots. Nonbonding valence electrons are never shown. A covalent bond is represented by a blank space between bonding atoms.

A covalent bond is represented as a line or as dots between atoms. A Lewis structure shows the number of covalent bonds between bonded atoms. Lone pair electrons are represented as pairs of dots.

Which of the following statements correctly describe formal charges and the skeletal arrangement of atoms in a Lewis structure? Select all that apply. For every compound, there will always be a Lewis structure in which all of the formal charges are zero. A structure in which nonzero formal charges are small is preferred to a structure in which they are large. A structure in which all formal charges are zero is preferred to a structure containing nonzero formal charges. If there are nonzero formal charges in a molecule, the best skeletal arrangement places them on the most electronegative atoms.

A structure in which nonzero formal charges are small is preferred to a structure in which they are large. A structure in which all formal charges are zero is preferred to a structure containing nonzero formal charges.

Which of the following statements correctly describe resonance structures? Select all that apply. Resonance structures are isomers of the same species. 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.

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

Select all the statements that correctly describe multiple bonds. A double bond arises when two atoms share two electrons between them. Bond strength increases with the number of electron pairs shared between two atoms. A multiple bond arises when a single central atom is bonded to several surrounding atoms. A multiple bond arises when two atoms share two or more electron pairs. Carbon frequently forms multiple bonds.

Bond strength increases with the number of electron pairs shared between two atoms. A multiple bond arises when two atoms share two or more electron pairs. Carbon frequently forms multiple bonds.

Using the table of electronegativity values provided, select all the bonds from the following list that are polar covalent. (Use the electronegativity difference guidelines specified in this text.) C-S C-N B-Cl Cl-Br H-O

C-N B-Cl H-O

Select all the statements that correctly describe electronegativity. Electronegativity is a relative quantity. Electronegativity describes the relative ability of an atom in a covalent bond to attract the shared electron pair(s). The most electronegative element is hydrogen because it has the smallest atomic size. Electronegativity can be determined by measuring the energy changes when an atom gains an electron. Electronegativity is another word for electron affinity.

Electronegativity is a relative quantity. Electronegativity describes the relative ability of an atom in a covalent bond to attract the shared electron pair(s).

Select all statements that correctly describe formal charge. Formal charge is the comparison of an atom's associated electrons with its isolated valence electrons. Formal charges represent the actual charges on atoms in a molecule. Formal charge can be used to determine the most plausible Lewis structure for a given compound. The formal charges of the atoms in a species must add up to zero.

Formal charge is the comparison of an atom's associated electrons with its isolated valence electrons. Formal charge can be used to determine the most plausible Lewis structure for a given compound.

Which of the following statements correctly describe polar and nonpolar covalent bonds? Select all that apply. A polar bond is a covalent bond in which electrons are shared equally. In a polar covalent bond the electron density is highest near the more electronegative atom. In a polar covalent bond the atom with the lower electronegativity is marked δ- because it has less electron density. A bond between atoms whose electronegativities differ by less than 0.5 is nonpolar.

In a polar covalent bond the electron density is highest near the more electronegative atom. A bond between atoms whose electronegativities differ by less than 0.5 is nonpolar.

A _________ structure represents the covalent bonds and nonbonding electrons for a given chemical compound.

Lewis

Which of the following options correctly defines resonance structures? Lewis structures that contain multiple bonds Lewis structures for the same species that have a different total number of electrons Lewis structures for the same species that differ in the placement 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 options correctly describe the general trends in electronegativity? Select all that apply. Electronegativity tends to increase as atomic size increases. Metals tend to have lower electronegativities than nonmetals. Electronegativity tends to decrease down a group of the periodic table. Electronegativity tends to decrease from left to right across a period of the periodic table.c Fluorine is the most electronegative element.

Metals tend to have lower electronegativities than nonmetals. Electronegativity tends to decrease down a group of the periodic table. Fluorine is the most electronegative element.

Which of the following elements contain 5 valence electrons per atom? Select all that apply. P Br As Se O

P, As

Using the table of electronegativities provided arrange the following bonds in order of increasing ionic character. (Place the least polar bond at the top of the list.) C-H Pd-H N-O F-Cl

Pd-H C-H N-O F-Cl

Which statement correctly defines the bond length of a covalent bond? The shortest distance between the two edges of the molecule, measured across the bonded atoms The distance from the nucleus of each atom to the edge of the molecule The distance between the outer edges of the two covalently bonded atoms The distance between the nuclei of the two covalently bonded atoms

The distance between the nuclei of the two covalently bonded atoms

Select all the statements that correctly describe the relationships between number of bonding electron pairs, bond length, and bond energy. The longer the bond the higher the bond energy. For a given pair of atoms, a single bond is shorter than a double bond. The shorter the bond, the greater the bond strength. For a given pair of atoms, a triple bond is stronger than a double bond.

The shorter the bond, the greater the bond strength. For a given pair of atoms, a triple bond is stronger than a double bond.

What does the symbol ↔ mean when used between two chemical structures? The two structures interconvert rapidly. The two structures are in equilibrium. The two structures are resonance forms of the same species. The two structures are equivalent.

The two structures are resonance forms of the same species.

Which electrons are shown in a Lewis structure? Only the valence electrons that are shared between atoms Every electron from every atom in a molecule The valence electrons of all atoms in a molecule The valence electrons of the central atom in a molecule

The valence electrons of all atoms in a molecule

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. a = -1; b = +1; c = -1 a = +1; b = -1; c = +1 a = 0; b = +1; c = -1 a = -1; b = 0; 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 _____. electrons; bonds electrons; atoms atoms; electrons bonding electrons; lone pair electrons

atoms; electrons

A pair of electrons shared between two atoms in a covalent bond is called a shared or _____________ electron pair, whereas an outer-level electron pair that is not involved in bonding is called an unshared or ____________ pair.

bonding, lone

True or false: All of the electrons in a many-electron atom can participate in covalent bonding.

false

A carbon-carbon double bond is ______ than a carbon-carbon triple bond, and ______ than a carbon-carbon single bond. longer, shorter longer, longer shorter, shorter shorter, longer

longer, shorter

The length of a covalent bond is the distance between the ________ of the two covalently bonded atoms.

nuclei

The _______ rule states that when atoms bond they may lose, gain, or _____________ electrons in order to attain an outer level containing eight electrons. Listen to the complete question

octet, share

Atoms bond in order to attain a full __________ level or shell of electrons. Elements in period 2 seek a total of __________ such electrons while period 1 elements such as hydrogen seek a total of ______________.

outer, 8, 2

A chemical bond in which electrons are shared unequally between two atoms is called a ________. _________ bond.

polar covalent

The dipole moment (μ) of a polar covalent bond is calculated as the _____ of the magnitude of the partial charges (Q) and the _____ between them. sum, square of the distance product, distance sum, distance product, square of the distance

product, distance

The number of bonding pairs of electrons, bond length, and bond energy are closely related. For a given pair of atoms, the greater the number of electron pairs shared between the atoms, the _____ and _____ the bond will be.

shorter, stronger

Between the same two atoms, the strongest covalent bond is the _____ bond and the weakest is the _____ bond. triple; double single; double single; triple triple; single

triple; single

True or false: As a general trend, elements with high first ionization energies (IE1) also have high electronegativity values.

true

In a Lewis structure of a molecule, only the ________ electrons are shown.

valence

In a many-electron atom, only the electrons at the ______ level will participate in covalent bonding. valence inner core

valence

The formal charge assigned to an atom is calculated by subtracting the number of electrons associated with the atom from the total number of ______ electrons. The number of electrons associated with a specific atom is defined as being the sum of the ______ electrons and half the ______ electrons. core, unshared, shared valence, shared, unshared valence, unshared, shared core, shared, unshared

valence, unshared, shared

When more than one skeletal arrangement of atoms is possible in a Lewis structure, formal charges can help determine the best arrangement. For molecules, a Lewis structure in which all of the formal charges are ______ is preferred to one that contains ______ formal charges. nonzero, zero positive, negative zero, nonzero negative, positive

zero, nonzero