Chapter 9

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 statements correctly describe a polar covalent bond? Select all that apply. Multiple select question.

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

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

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. Multiple choice question.

solids; decrease; weaker

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

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

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)

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

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

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. Multiple select question.

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. Electron density relief maps show a steady increase in electron sharing from NaCl to Cl2.

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. Multiple choice question.

Electronegative; increases

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

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

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

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

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

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

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.

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. Multiple select question.

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.

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

Low melting point

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

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

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

Nonconductors in the solid state High melting points

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. Multiple select question.

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

Which of the following properties is common to BOTH molecular covalent substances and network covalent substances? Multiple choice question.

Poor electrical conductivity in any phase

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

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

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 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.

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

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 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

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

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. Multiple choice question.

decreases; more; increase; decrease

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

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

From left to right, Period 3 chlorides exhibit a gradation in bond type from ______ to ______ to ______. Multiple choice question.

ionic; polar covalent; nonpolar covalent