AP Chem Unit 2

Silicon dioxide, SiO2

A network solid with covalent bonding.

Which of the following molecules has the shortest bond length? A) N2 B) O2 C) Cl2 D) Br2 E) I2

A) N2

H-C=C-HWhat is the hybridization of the carbon atoms in a molecule of ethyne, represented above? A) sp B) sp2 C) sp3 D) dsp2 E) d2sp

A) sp

On the basis of strength of intermolecular forces, which of the following elements would be expected to have the highest melting point?

Br2

Of the following single bonds, which is the LEAST polar? A) N—H B) H—F C) O—F D) I—F E) O—H

C) O—F

The molecule with only one double bond

C2H4

which of the following complete lewis diagrams represents a molecule with a bond angle that is closest to 120º?

C2H4O2 but as a picture ya feel

Types of hybridization exhibited by the C atoms in propene, CH3CHCH2, include which of the following? I. sp II. sp2 III. sp3

II and III only

Which of the following has a zero dipole moment? A) HCN B) NH3 C) SO2 D) NO2 E) PF5

E) PF5

In solid methane, the forces between neighboring CH4 molecules are best characterized as

London (dispersion) forces

Which of the following molecules has a dipole moment?

PF3

Of the following pure substances, which has the highest melting point?

SiO2

the potential energy as a function of internuclear distance for three diatomic molecules, X, Y, Z is shown in the graph above. based on the data in the graph, which of the following correctly identifies the diatomic molecules x y z?

X: H2 Y: N2 Z: O2

which of the following atoms or ions has exactly two unpaired electrons

Zr2+

Solid ethyl alcohol, C2H5OH

a molecular solid with hydrogen bonding

In a molecule in which the central atom exhibits sp3d2 hybrid orbitals, the electron pairs are directed toward the corners of

an octahedron

The best explanation for the fact that diamond is extremely hard is that diamond crystals

are giant molecules in which each atom forms strong covalent bonds with all of its neighboring atoms

in the reaction represented above, what is the hybridization of the C atoms before and after the reaction occurs?

before: sp2 after: sp3

In the reaction represented above, what is the hybridization of the C atoms before and after the reaction occurs

sp2, sp3

lewis electron dot diagrams for CO2 and SO2 are given above. The molecular geometries and polarity of the two substances are

different because the lone pair of electrons on the S atom make it the negative end of a dipole

The SbCl5 molecule has trigonal bipyramid structure. Therefore, the hybridization of Sb orbitals should be

dsp3

copper and zinc atoms have the same atomic radius 135 picometers. based on this information, which of the following diagrams best represent an alloy containing only copper and zinc atoms.

even atoms all in a straight line and straight columns and all identical.

Is used to explain the fact that the four bonds in methane are equivalent

hybridization

CH3CH2OH boils at 78 °C and CH3OCH3 boils at - 24 °C, although both compounds have the same composition. This difference in boiling points may be attributed to a difference in

hydrogen bonding

Is used to explain why the boiling point of HF is greater than the boiling point of HBr

hydrogen bonding

the diagram above shows two resonance structures for a molecule of C6H6. the phenomenon shown in the diagram best supports which of the following claims about the bonding . in C6H6?

in the C6H6 molecule, all the bonds between the carbon atoms have the same length

according to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4 and NH3 and H2O is best accounted for by the

increasing number of unshared pairs of electrons

According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the

increasing the number of unshared pairs of electrons

which of the following scientific claims about the bond in the molecular compound HF is most likely to be true?

the bond is highly polar

Which of the following molecules has the shortest bond length? (A) N2 (B) O2 (C) Cl2 (D) Br2 (E) I2

(A) N2

In which of the following groups are the three species isoelectronic; i.e., have the same number of electrons? (A) S2-, K+, Ca2+ (B) Sc, Ti, V2+ (C) O2-, S2-, Cl- (D) Mg2+, Ca2+, Sr2+ (E) Cs, Ba2+, La3+

(A) S2-, K+, Ca2+

The boiling points of the elements helium, neon, argon, krypton, and xenon increase in that order. Which of the following statements accounts for this increase? (A) The London (dispersion) forces increase. (B) The hydrogen bonding increases. (C) The dipole-dipole forces increase. (D) The chemical reactivity increases. (E) The number of nearest neighbors increases.

(A) The London (dispersion) forces increase.

which of the following lewis diagrams best represents the bonding in the N2O molecule considering formal charges

(Actual picture of the Lewis structure) 2NIIINI6O

Which of the following describes the changes in forces of attraction that occur as H2O changes phase from a liquid to a vapor? (A) H—O bonds break as H—H and O—O bonds form. (B) Hydrogen bonds between H2O molecules are broken. (C) Covalent bonds between H2O molecules are broken. (D) Ionic bonds between H+ ions and OH- ions are broken. (E) Covalent bonds between H+ ions and H2O molecules become more effective.

(B) Hydrogen bonds between H2O molecules are broken.

Of the following pure substances, which has the highest melting point? (A) S8 (B) I2 (C) SiO2 (D) SO2 (E) C6H6

(C) SiO2

According to the VSEPR model, the progressive decrease in the bond angles in the series of molecules CH4, NH3, and H2O is best accounted for by the (A) increasing strength of the bonds (B) decreasing size of the central atom (C) increasing electronegativity of the central atom (D) increasing number of unshared pairs of electrons (E) decreasing repulsion between hydrogen atoms

(D) increasing number of unshared pairs of electrons

Of the following compounds, which is the most ionic? (A) SiCl4 (B) BrCl (C) PCl3 (D) Cl2O (E) CaCl2

(E) CaCl2

which of the following complete lewis diagrams represent a molecule containing a bond angle that is closest to 120 degrees

(diagram answer) 4H2C3O

Which of the following is not a valid resonance structure for N3-?

(diagram) 4NII2NI6N

choose the electron dot formula that most accurately describes the bonding in CS2

(diagram) 4SII4CII4S

steel is an alloy containing Fe atoms and C atoms. Which of the following diagrams represents the particle level structure of steel

(diagram) Large Fe Small C atoms

the particle-level diagram represents the structure of solid KF. although the molar mass of KCl is greater than that of KF, the density of KCl is actually less than that if KF. why?

+-+ -+- +-+ the minus are big and the plus are small

C2H4(g) + 3 O2(g) 2 CO2(g) + 2 H2O(g)For the reaction of ethylene represented above, H is -1,323 kJ. What is the value of H if the combustion produced liquid water H2O(l) ? (H for the phase change H2O(g) H2O(l) is -44 kJ mol

-1,411 kJ

How many resonance structures can be drawn for O3?

2

(A) CO2 (B) H2O (C) CH4 (D) C2H4 (E) PH3 3. The molecule with only one double bond 4. The molecule with the largest dipole moment 5. The molecule that has trigonal pyramidal geome¬try

3. (D) C2H4 4. (B) H2O 5. (E) PH3

(A) A network solid with covalent bonding (B) A molecular solid with zero dipole moment (C) A molecular solid with hydrogen bonding (D) An ionic solid (E) A metallic solid 8. Solid ethyl alcohol, C2H5OH 9. Silicon dioxide, SiO2

8. (C) A molecular solid with hydrogen bonding 9. (A) A network solid with covalent bonding

What is the identity of the metal chloride? A) NaCl B) KCl C) CuCl D) LiCl

B) KCl

Resonance is most commonly used to describe the bonding in molecules of which of the following? A) CO2 B) O3 C) H2O D) CH4 E) SF6

B) O3

For which of the following molecules are resonance structures necessary to describe the bonding satisfactorily? A) H2S B) SO2 C) CO2 D) OF2 E) PF3

B) SO2

Is a polar molecule A) BeCl2 B) SO2 C) N2 D) O2 E) F2

B) SO2

has a central atom with less than an octet of electrons

BH3

In which of the following processes are covalent bonds broken?

C (diamond) C (g)

Which of the following molecules contains only single bonds?

C2H5

Which of the following molecules has a dipole moment of zero?

C6H6 (benzene)

which of the following molecules is nonpolar but has polar covalent bonds?

CCl4

Pi (π) bonding occurs in each of the following species EXCEPT (A) CO2 (B) C2H4 (C) CN- (D) C6H6 (E) CH4

CH4

Which of the following is a nonpolar molecule that contains polar bonds?

CO2

the electron pair in a C-F bond could be considered

Closer to F because Fluorine has a higher electronegativity than carbon.

The London (dispersion) forces are weakest for which of the following gases under the same conditions of temperature and pressure?

H2

The electron-dot structure (Lewis structure) for which of the following molecules would have two unshared pairs of electrons on the central atom?

H2S

Of the following molecules, which has the largest dipole moment?

HF

The liquefied hydrogen halides have the normal boiling points given above. The relatively high boiling point of HF can be correctly explained by which of the following?

HF molecules tend to form hydrogen bonds

The melting point of MgO is higher than that of NaF. Explanations for this observation include which of the following? I. Mg2+ is more positively charged than Na+. II. O2- is more negatively charged than F-. III. The O2- ion is smaller than the F- ion.

I and II only

two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. which of the following is the most valid scientific claim that can be made about the compound.

It contains iconic bonds

the lattice energy of a salt is related to the energy required to separate the ions. for which of the following pairs of ions is the energy that is required to sperate ions largest

Mg+2 and O-2

which of the following atoms cannot exceed the octet rule in a molecule

N

Contains 1 sigma (s) and 2 pi (p) bonds

N2

Has the largest bond-dissociation energy

N2

At 25 °C and 1 atm, has molecules with a pyramidal shape.

NH3

has a trigonal pyramidal molecular geometry

NH3

which of the following has an incomplete octet in its lewis structure

NO

which has the greater bond length, No2- or NO3-?

NO3-

Which of the following compounds is ionic and contains both sigma and pi covalent bonds?

NaCN

Of the following single bonds, which is the LEAST polar?

O - F

which of the following has a bond order of 2

O2

Which of the following molecules has an angular (bent) geometry that is commonly represented as a resonance hybrid of two or more electron-dot structures?

O3

The atom that contains exactly two unpaired electrons

S

forms monoatomic ions with 2^- charge in solutions

S

in which of the following groups are the three species isoelectric

S-2, K+, Ca2+

for which of the following molecules are resonance structures necessary to describe the bonding satisfactorily?

SO2

consider atoms of the following elements. Assume that the atoms are in the ground state. The atom that contains exactly 3 unpaired electrons

Sb

Which of the following elements combines with oxygen to form a covalent network solid?

Si

Carbon dioxide, CO2(s)

Strong multiple covalent bonds (including p-bonds) with weak intermolecular forces

Methane, CH4 (s)

Strong single covalent bonds with weak intermolecular forces

which of the following scientific claims about the bond in the molecular compound in HF is most likely to be true

The bond is highly polar

The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms the C and Se is most likely to be true?

The carbon to selenium bond is nonpolar covalent

The energy required to dissociate an ionic solid into gaseous ions (lattice energy) for the compounds NaF and MgF2 is shown in the table above. On the basis of coulombs law. which of the following best helps explain the large difference between the lattice energies of NaF and MgF2

The charge of the Mg cation is larger than that of the Na cation

Which of the following best helps explain why the electronegativity of Cl is less than that of F?

When CL and F form bonds with other atoms, The cl bonding electrons are more shielded from the positive Cl nucleus than the F bonding electrons are shielded from the positive F nucleus.

two pure elements react to form a compound. one element is an alkali metal, X, and the other element is a halogen, Z. which of the following is the most valid scientific claim that can be made about the compound?

it contains ionic bonds

which of the following correctly indicates whether the solid represented by the particulate model conducts electricity and explains why or why not?

it does not conduct electricity because its ions cannot move freely within the solid

which of the following correctly indicates whether the solid represented by the particle model shown to the left conducts electricity and explains why or why not?

it does not conduct electricity because its ions cannot move freely within the solid.

Is used to explain the fact that the carbon-to-carbon bonds in benzene, C6H6, are identical

resonance

H-C----C-H what is the hybridization of the carbon atoms in a molecule of ethyne, represented above?

sp

What is the hybridization of the carbon atom in a molecule of ethyne, represented above?

sp

CCl4, CO2, PCl3, PCl5, SF6 Which of the following does not describe any of the molecules above?

square planar

copper atoms and zinc atoms have the same atomic radius, 135 picometers. based on this information, which of the following diagrams best represents an alloy containing only copper and zinc atoms

the 5x5 thats mostly light ones and they're all the same size

the elements C and Se have the same electronegativity value, 2.55. which of the following claims about the compound that forms from C and Se is most likely to be true?

the carbon to selenium bond is non-polar covalent

The geometry of the SO3 molecule is best described as (A) trigonal planar (B) trigonal pyramidal (C) square pyramidal (D) bent (D) bent

trigonal planar

The Bf3 molecule is nonpolar, whereas the NF3 molecule is polar. Which of the following statements accounts for the diffrence in polarity of the two molecules?

unlike BF3 NF3 has a nonpolar geometry due to an unshared pair of electrons on the N atom

the BF3 molecule is nonpolar, whereas the NF3 molecule is polar. what accounts for the difference in polarity?

unlike BF3, NF3 has a polar geometry due to an unshared pair of electrons on the N atom

Is used to explain why iodine molecules are held together in the solid state

van der Waals forces (LD forces)

which of the following Lewis diagrams best represents the bonding in the N2O molecule, considering formal charge?

••N---N-O••••••