Chapter 10

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; dots

Free radical

lone unpair electron

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; 5A; 7A

Why is BeF2 a nonpolar molecule?

BeF2 is linear and therefore the individual bond dipoles cancel to give no net dipole.

A species that contains a lone (unpaired) electron is referred to as ______. Select the best answer. Multiple choice question.

a free radical

A structure containing a central atom with two electron groups, designated AX2, has a _____ shape with a bond angle of _____ degrees.

linear; 180

Which of the following statements correctly describe how to draw a Lewis structure? Select all that apply

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

Which of the following statements correctly describe the effect of molecular polarity on the behavior of a molecular compound? Select all that apply.`

A polar compound will experience stronger intermolecular forces than a nonpolar compound. The physical properties of a molecular compound are directly related to molecular polarity.

Which of the following statements correctly describe the relative stabilities of resonance forms? Select all that apply.

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.

Which of the following statements correctly describe resonance structures? Select all that apply.

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

Resonance structures are Lewis structures that have the same relative placement of _____ but a different arrangement of _____. Multiple choice question.

Atoms; electrons

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

Cl S Xe

Which statement correctly describes the basic principle of VSEPR theory?

Each group of valence electrons around a central atom is located as far from the others as possible.

Which of the following statements correctly describe formal charge? Select all that apply. Multiple select question.

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.

Which of the following statements correctly describe how to determine whether a given molecule is polar or nonpolar? Select all that apply.

If a molecule contains no dipole moments across any bonds, it will be nonpolar. If the individual bond dipoles do not cancel, the molecule is polar. For a molecule that has polar bonds, the geometry must be known in order to predict the overall polarity.

When are multiple bonds needed in a Lewis structure?`

If one or more atoms do not have an octet of electron but all electrons have already been placed

Which of the following options correctly defines resonance structures?

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

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

Which of the following are odd-electron species? Select all that apply.

NO2 ClO

Which of the following statements correctly describe how formal charge is assigned to an atom in a Lewis structure? Select all that apply.

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

Which option correctly describes a covalent species that has four electron groups around the central atom? Select all that apply. Multiple select question.

The ideal bond angle for a four-electron system is 109.5o. If all four electron pairs are bonding pairs, the shape of the system is tetrahedral. A bent shape is observed if there are two bonding pairs and two lone pairs.

Which of the following statements correctly describe how to determine molecular shape using the VSEPR model? Select all that apply.

Use the molecular formula to draw the Lewis structure. The total number of shared and unshared electron pairs around the central atom gives the electron-group arrangement.

A five-electron group system (shown) has two different types of positions for substituents. The three positions marked "1" form a trigonal plane about the central atom and are called _____ positions while the two positions marked "2" are _____ positions. Lone pairs prefer to occupy the _____ positions.

equatorial; axial; equatorial

Molecular polarity has a direct effect on the behavior of molecular compounds. The attractive forces between polar molecules are _____ than those between nonpolar molecules. It therefore takes _____ energy to separate polar molecules from each other, and a polar compound will have a _____ boiling point than a nonpolar compound of similar size.

stronger; more;higher