Chemistry chapter 9 smartbook questions

Select all the structures in which the polarity of the bond has been marked correctly.

A, D, E

The bond __________is given by the number of electron pairs shared between two bonded atoms. For a double bond such as C=O, this number is _____________because there is/are________________ electron pair(s) shared between the two atoms.

order 2 2

Which of the following accounts for the malleability of metals?

Mobility of valence electrons

The melting point of a pure metal correlates to the strength of its metallic bonding. In general, melting points ______ down a group and ______ across a period.

decrease; increase

NaCl SiCl4 Cl2

Ionic Polar Covalent Nonpolar Covalent

Which of the following is not a general physical property of metals? (Excludes mercury.)

Low melting point

Which of the following are characteristic properties of metals? Select all that apply.

Metals can be shaped without breaking. Metals conduct electricity in the solid and liquid states.

Which of the following statements correctly describe trends in lattice energy? Select all that apply.

The lattice energy of an ionic compound tends to decrease as ionic size increases. NaCl is expected to have a higher lattice energy than NaBr.

The bond formed between two nonmetals, which are usually very similar in their tendency to lose or gain electrons, is the _____ bond. This bond involves the _____ of one or more electron pairs between the two atoms.

covalent; sharing

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

The energy required to overcome the attraction between two bonded nuclei and their shared electrons is called _____ energy. This quantity is a measure of bond strength since the stronger the bond, the _____ the amount of energy required to break it.

bond; greater

The bond typically observed when a metal bonds to a nonmetal is the _____ bond. The metal atom _____ one or more valence electrons while the nonmetal _____ electrons.

ionic; loses; gains

When calculating the oxidation numbers of atoms in a bond, the more electronegative atom is assigned ______ of the shared electrons and the less electronegative atom is assigned ______.

All; none

Using the table of electronegativity values provided, which of the following bonds are polar covalent? Select all that apply.

H-O C-N B-Cl

Which of the following options correctly relate the physical properties of ionic solids to the nature of the ionic bond? Select all that apply.

Ionic solids are brittle because any impact causes ions of the same charge to be pushed together. Repulsion causes the solid to crack. Ionic solids are fairly rigid due to the arrangement of the ions in a regular crystal lattice.

Which of the following options correctly describe lattice energy? Select all that apply.

Lattice energy provides a measure of the strength of an ionic bond. Lattice energy is the energy required to separate 1 mol of an ionic solid into gaseous ions.

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.)

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

A covalent bond in which the electrons are shared unequally is called a(n) _____________covalent bond. The atoms of the bond have partial negative and positive_____________ due to unequal electron distribution.

Polar Charges

Which of the following properties is common to BOTH molecular covalent substances and network covalent substances?

Poor electrical conductivity in any phase

The formation of an ionic bond involves a number of different processes. If we consider the separate electron transfer processes involved in the formation of sodium chloride, which individual steps would require an input of energy? The overall process is represented by the equation shown below. Select all that apply. 2Na (s) + Cl2 (g) → 2NaCl (s)

Removal of an electron from Na Dissociation of Cl2 to form 2Cl Conversion of Na (s) → Na (g)

Covalent bond Ionic bond Metallic bond

Sharing of electrons between two atoms due to the attraction between the nucleus of each atom and the electrons of the other The attraction between two oppositely charged particles formed by the transfer of electrons between two atoms Sharing of all valence electrons as an "electron sea" by all the atoms of the substance

Which of the following options correctly describe the relationships between bond order, bond length, and bond energy? Select all that apply.

The shorter the bond, the greater the bond strength. For a given pair of atoms, a higher bond order means a shorter bond.

Bond order, bond length, and bond energy are closely related. The shorter a bond, the _____ its bond strength. A shorter bond will therefore have a higher bond energy than a longer bond. Bond order also plays a role. For a given pair of atoms, the higher the bond order, the shorter and _____ the bond will be.

greater; stronger

Which of the following factors affect the magnitude of the lattice energy for an ionic compound? Select all that apply.

The arrangement of the ions in the crystal The size of the ions The charges of the ions

It is possible for two covalently bonded atoms to share more than one electron pair. For example, in a double bond there are _____ shared electron pairs, making a total of _____ shared electrons, and the bond order is _____.

2; 4; 2

Which of the following options correctly describe the general trends in electronegativity? Select all that apply.

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.

Which of the following are characteristic properties of ionic compounds? Select all that apply.

High melting points Nonconductors in the solid state

Metallic bond Covalent bond Ionic bond

Two or more Metal atoms Nonmetal to nonmetal Metal to nonmetal

Bonds in fuels are ___________than those of their combustion products, making the overall reactions exothermic.

Weaker

The relative ability of a bonded atom to attract shared electron pairs is called its _____. This ability _____ as the size of the atom decreases because for a smaller atom the shared electrons will be closer to the nucleus.

electronegativity; increases

The greater the ΔEN between bonded atoms, the ______ the partial charges on the atoms and the ______ the partial ionic character of the bond.

larger; higher

In general, the formation of a bond between two or more atoms ______. (Select all that apply.)

produces a more stable system lowers the potential energy between oppositely charge particles

When the elements Mg and Cl form an ionic bond, Mg loses ____________________electron(s) from the 3s orbital to form the Mg2+ cation. Cl gains __________________electron(s) in the 3p orbital to form the Cl- anion. Since the total number of electrons lost always equals the total number of electrons gained, the compound formed will contain ________________Mg2+ ion(s) for every_____________________ Cl- ion(s). Fill in the blanks with the appropriate numbers.

2 1 1 2

The covalently bonded species shown has _____ bonding pair(s) of electrons and _____ lone pair(s).

3;1

Which option correctly describes the influence of electronegativity difference (ΔEN) on bond character? Select all that apply.

A bond with ΔEN greater than 1.7 is considered to be mostly ionic. A bond with ΔEN of 0.4 or less is considered mostly covalent.

Which of the following statements correctly describe bond energy? Select all that apply.

Bond energy is equal in magnitude to the energy released when a bond is formed. Bond energy is a measure of bond strength. Bond energy is the energy required to break a covalent bond.

Arrange the following ionic compounds in order of increasing lattice energy (increasing strength of the ionic bond) based on general trends in lattice energy. Start with the compound that has the lowest lattice energy at the top of the list. Instructions

CaBr2 MgCl2 Li2O

Most covalently bonded substances consist of individual separate molecules. Each individual molecule is held together by means of strong _____________bonds between the atoms. In addition, there are weak forces of attraction between the individual molecules, called ___________forces.

Covalent Intermolecular

The bond formed between two nonmetal atoms is called a(n)__________bond. This type of bond arises from the net attraction between the__________________of each atom and the electrons of the other, and results in electrons being______________between the two atoms.

Covalent Nucleus Shared

The bonding of chlorine with each of the Period 3 elements shows a change in bonding type from ionic through polar covalent to nonpolar covalent. Select the properties that reflect this change in bonding character.

Electron density relief maps show a steady increase in electron sharing from NaCl to Cl2. Electrical conductivity at the melting point is high only for chlorides of Group 1A(1) and Group 2A(2). There is a general decrease in ΔEN moving from left to right across the period.

Which of the following options correctly describe electronegativity? Select all that apply.

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

True or false: A molecular covalent substance (such as CO2) has a low melting point because the covalent bonds that hold the molecules together are weak and do not require much energy to break.

False

Which of the following statements correctly describe a polar covalent bond? Select all that apply.

In a polar covalent bond the electron density is highest over the more electronegative atom. A bond between atoms whose electronegativities differ by more than 0.4 but less than 1.7 is polar.

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

In a stable covalent bond, nucleus-electron attractions dominate the system. Formation of a covalent bond results in increased electron density between the two nuclei. If the two atoms in a covalent bond approach too closely, the system will become less stable.

Why does an ionic solid not conduct electricity in the solid state but is a good conductor when melted or dissolved in water? Select all that apply.

In the liquid or dissolved state, the ions are free to move and can carry an electric current. In the solid state, the ions are held in specific positions and are not free to move.

Which of the following options correctly defines intermolecular forces?

Intermolecular forces are the weak forces of attraction found between the individual molecules of a molecular covalent substance.

Which of the following statements correctly describe ionic bonding? Select all that apply.

Ionic bonding involves the transfer of electrons from the metal to the nonmetal. An ionic bond is the electrostatic attraction between two oppositely charged ions.

An electric current is carried by the movement of either electrons or_________________ . In a metal, the valence electrons form a(n) ______________electron sea and are therefore free to move even in the solid state. A metal therefore conducts electricity in both the solid and the liquid state. In addition, the freely moving electron sea allows energy to be transferred readily so that metals are also good conductors of__________________ .

Ions Delocalized Heat

Consider the formation of an ionic bond between the elements potassium (K) and chlorine (Cl). Which of the following statements describe this process correctly? Select all that apply.

K loses one electron from its 4s orbital to form a K+ cation. The total number of electrons lost equals the total number of electrons gained. Both the K+ and Cl- ions have full outer shells containing 8 electrons.

Arrange the following ionic compounds in order of decreasing lattice energy (decreasing strength of the ionic bond) based on general periodic trends. Start by placing the compound with the highest lattice energy at the top of the list.

MgO Na2O KBr

The high electrical and thermal conductivity of metals can be explained by the electron-sea model in which valence electrons are ______.

Mobile

Select the correct statements describing molecular covalent solids. Select all that apply.

Molecular covalent solids have intermolecular forces between molecules. Molecular covalent solids have low melting and boiling points Molecular covalent solids are either soft or hard but brittle.

ΔEN = 0 ΔEN < 0.4 ΔEN between 0.4 - 1.7 ΔEN > 1.7

Nonpolar Covalent Mostly covalent Polar Covalent Ionic

Which of the following options correctly reflect how to calculate the oxidation number (O.N.) of a covalently bonded atom using electronegativity? Select all that apply.

O.N. = (valence electrons) - (assigned shared electrons + unshared electrons) An atom in a bond is assigned all its unshared electrons.

An ionic solid does not conduct electricity in the solid state because the ions are held together by_____________ attractive forces and cannot move from their positions in the crystal structure. If the solid melts or dissolves in water, the ions are free to move and carry a(n)_______________ current.

Strong Electric

Which of the following options describe how to draw the Lewis electron-dot symbol for a given element? Select all that apply.

The Lewis symbol includes only the valence electrons for the element. The A-group number of the element gives the number of valence electrons. One dot is placed on each side of the element symbol before pairing any dots.

Which statement below correctly describes an ionic compound?

The compound is a solid at room temperature, does not conduct electricity, and dissolves in water to give a solution that conducts electricity.

Which statement correctly describes the general characteristics of a covalent bond? Select all that apply.

The covalent bond involves the attraction between the nucleus of each atom and the electrons of the other. A covalent bond involves the sharing of electrons between two atoms.

Select the statement that correctly explains the source of the energy change in a chemical reaction.

The main contribution to ΔH is the difference in the bond energies of reactants and products.

Select the statement that explains why metals can be shaped with a hammer without breaking.

The metal cations are not held rigidly in place and are able to slide past each other when the metal is struck with a hammer.

Which of the following options correctly explain the differences in physical behavior of molecular covalent substances and network covalent substances? Select all that apply.

The strong covalent bonds that hold the atoms of a network covalent substance together require a lot of energy to break. The relatively low boiling points of molecular substances reflect the strength of the intermolecular forces between the individual molecules.

Select the statement that correctly summarizes the steps to calculate ΔHo of a reaction using bond enthalpies.

The sum of the bonds formed (exothermic) in the reaction is subtracted from the sum of the bonds broken (endothermic).

Select all the statements that correctly describe the electron-sea model of metallic bonding.

The valence electrons of the bonded atoms are shared in an electron sea. Two or more metals can combine to form alloys of variable composition by sharing their valence electrons.

The simplest model used to describe the bonding in metals is the electron-sea model. In terms of this model, all the metal atoms contribute their ________________electrons to form an electron "sea" so that the electrons are______________ or shared among all the atoms. The metal is held together by the attraction between the metal _______________and the sea of electrons.

Valence Pooled Ions

To draw the Lewis electron-dot symbol for a main-group element, first determine the number of ______________________electrons by noting the ___________________number of the element. Place one______________________ for each electron on each of the four sides of the element symbol, pairing them up once each site has an electron.

Valence, Group, Dot

The enthalpy of a reaction, ΔHrxn, is the overall heat change resulting from ______ energies when reactant bonds break and ______ energies when product bonds form.

absorbing; releasing

The formation of an ionic compound involves the transfer of electrons. The removal of one or more electrons from a metal is a process that _____ energy, whereas the addition of one or more electrons to a nonmetal _____ energy.

absorbs; releases

In general, electronegativity _____ as atomic size increases because a shared electron pair is closer to the nucleus of a smaller atom, which therefore attracts these electrons _____ strongly. Electronegativity tends to _____ from left to right across a period of the periodic table and tends to _____ down a group.

decreases; more; increase; decrease

The partial ionic character of a bond is related to the difference in the electronegativities of the bonded elements. The greater the ΔEN, the___________________ the percent ionic character of the bond. Although there are many bonds that have 0% ionic character, no bond has 100% ionic character, which indicates that electron ____________________occurs to some extent in every bond.

greater Sharing

The bond length of a covalent bond is the distance between the nuclei of two bonded atoms. The larger the atoms, the _____ this distance will be. Bond length therefore _____ as atomic size decreases.

greater; decreases

The percent ionic character of a bond ______ with ΔEN. An arbitrary value of ______ divides ionic from covalent bonding.

increases; 50% ionic character

For a series of similar covalent bonds, bond length _____ as atomic size increases. A C-O bond would therefore be _____ than a Si-O bond.

increases; shorter

As the ΔEN for a particular bond increases, the character of the bond changes and this is often reflected in the behavior of a substance. The ΔEN for the K-Br bond is 2.0 and ΔEN for the Au-Br bond is 0.4. Match each statement about the K-Br and Au-Br bonds correctly to the descriptions. The K-Br bond is more The Au-Br bond is more KBr is expected to have AuBr3 is expected to have

ionic in character. covalent in character. a relatively high melting point. a relatively low melting point.

The amount of energy required to separate 1 mole of ions in a crystalline solid into separate gaseous ions is called _____ energy. This energy provides a measure of the strength of a(n) _____ bond, since the stronger the bond, the _____ the amount of energy required to break it.

lattice; ionic; greater

Fuels with fewer weak bonds yield ______ energy than fuels with more weak bonds.

less

A polar bond is a covalent bond in which there is an electronegativity difference between the two bonded atoms and electrons are shared unequally. The atom with the higher electronegativity will have a partial _____ charge and is marked with the symbol _____ while the atom with the lower electronegativity will have a partial _____ charge and is marked with the symbol _____.

negative; δ-, positive; δ+

In general the formation of a chemical bond lowers the _____ energy of a chemical system, leading to a _____ stable arrangement.

potential; more

Most metals are _____ at room temperature and generally have moderate to high melting and boiling points because the metallic bond is fairly strong. The melting point of a metal will _____ as atomic size increases because larger metal ions have a _____ attraction for the electron sea.

solids; decrease; weaker

Ionic compounds are hard and brittle because ______.

strong attractive forces hold ions in specific positions

Which of the following options correctly describe the procedure used to calculate ΔH for a reaction using bond energies? Select all that apply.

ΔH for the reaction is given by (sum of ΔHbonds broken) + (sum of ΔHbonds formed) The sum ΔHbonds broken is given a positive value.