Chem exam 3 7 and 8

How many lone pairs of electrons are on the I atom in IF5?

1

Which of the following would be expected to have sp2 hybridization on atom A?

1, 2 and 3

What is the F-B-F bond angle in BF3? less than 109.5° 109.5° greater than 120° 120°

120°

Consider a molecule with the following connections: When a valid electron dot structure is written, how many double bonds will the molecule contain? 0 1 4 2

2

How many carbon-carbon bonds are present in C3H8? 3 0 2 1

2

What is the bond order of the OO bond in O2?

2

What is the bond order of the OO bond in O2? 0 1 2 3

2

The nitrogen-nitrogen bond in :N≡N: has a bond order of 1 3 6 2

3

How many lone pairs are there in the Lewis structure of O2?

4

How many lone pairs are there in the Lewis structure of O2? 4 0 3 1

4

What is the smallest bond angle in SF6? 120° 60° 109.5° 90°

90°

Which of these is one of the reasons why hybridization of atomic orbitals explains the bonding in methane, CH4 better than considering atomic orbitals. Hydrogen is too small an atom for its atomic orbital to overlap with a carbon atomic orbital. Hybridization raises the energy of all atomic orbitals. Hybridization lowers the energy of all atomic orbitals. A ground state carbon atom has two unpaired electrons.

A ground state carbon atom has two unpaired electrons.

Which of the following is not a valence bond concept? The greater the overlap between the orbitals on two atoms, the stronger the bond. Lone pair electrons are in atomic orbitals or in hybrid atomic orbitals. Atomic orbitals on two atoms may overlap to form antibonding orbitals. A pair of electrons in a bond is shared by both atoms.

Atomic orbitals on two atoms may overlap to form antibonding orbitals.

Use the following MO diagram for Be2, Be2+, and Be2-. Based on this diagram,

Be2+ and Be2- are both more stable than Be2.

In the most acceptable electron-dot structure for carbonyl fluoride, COF2 the central atom is C, which is doubly-bonded to O. O, which is doubly-bonded to C. O, which is singly-bonded to C C, which is singly-bonded to O.

C, which is doubly-bonded to O.

Which compound, shown with its dipole moment, is expected to exhibit the smallest percent ionic character? NaI HCl CBr2Cl2 CBr4

CBr4

Which of the following molecules has polar bonds but has no net dipole? CH3Cl CCl4 CHCl3 NH3

CCl4

Which molecule contains the most polar bonds? CBr4 CF4 SeO2 CN-

CF4

Which of the following compounds exhibits hydrogen bonding? CH3CH2OH CH3F (CH3)3N CH3OCH3

CH3CH2OH

Which of the following molecules does not have a dipole moment? PH3 HBr CH3OH CH3CH3

CH3CH3

Which of the following molecules will readily form hydrogen bonds with H2O? CH3OH C3H8 H2 CH4 P

CH3OH

Which molecule has the weakest bonds? CCl4 CBr4 CI4 CF4

CI4

Which of the following should have the largest dipole moment? CsBr(g) CCl2F2(g) H2(g) CO2(g)

CsBr(g)

which bond in each of the following pairs is more polar. C−H or C−Cl

C−Cl

Which of the following covalent bonds has higher bond dissociation energy? H-C H-F H-O H-S

H-F

Which molecule contains the most easily broken carbon-carbon bond? F2C=CF2 H3C−CH3 HC≡CH H2C=CH2

H3C−CH3

Which of the following compounds exhibits only dispersion and dipole-dipole intermolecular interactions? HBr H2O N2 CO2

HBr

A molecule with the formula XF3 where the element X has the hybridization sp3. Which of the following elements could be X? N B Si C

N

Of the following elements, which has the highest electronegativity? Si Ga N Cd

N

A molecular compound that obeys the octet rule in which all atoms have a zero formal charge is XeF4. BrF3. NCl3. CaBr2.

NCl3.

Which is the longest bond? N−H N≡N N=N N−N

N−N

What happens as two hydrogen atoms approach each other and the distance between the two nuclei decreases?

Repulsive forces increase and are greater than the attractive forces.

which bond in each of the following pairs is more polar. −Li or Si−Cl

Si−Cl

The C=O bond in COCl2 can be described as a σ bond and a π bond, both involving sp hybrid orbitals on C. a σ bond and a π bond, both involving sp 2 hybrid orbitals on C. a σ bond involving an sp hybrid orbital on C and a π bond involving a p orbital on C. a σ bond involving an sp 2 hybrid orbital on C and a π bond involving a p orbital on C.

a σ bond involving an sp 2 hybrid orbital on C and a π bond involving a p orbital on C

A nitrogen atom in N2 should have a

charge of 0.

A nitrogen atom in N2 should have a charge of 0. charge of 1-. partial charge δ−. partial charge δ+.

charge of 0.

Which drawing best represents hydrogen bonding?

drawing 3

Which electrostatic forces hold atoms together in a molecule? electron-nucleus forces nucleus-nucleus forces electron-electron forces all three forces

electron-nucleus forces

The electronegativity for both sulfur and carbon is 2.5. Therefore the compound CS2 would be expected to be ionic with C as the cation. have polar covalent bonds between C and S. be ionic with C as the anion. have nonpolar covalent bonds between C and S.

have nonpolar covalent bonds between C and S.

The electronegativity is 2.1 for H and 3.0 for N. Based on these electronegativities, NH4 + would be expected to be ionic and contain H+ ions. have polar covalent bonds with a partial negative charges on the H atoms. have polar covalent bonds with a partial positive charges on the H atoms. be ionic and contain H- ions.

have polar covalent bonds with a partial positive charges on the H atoms.

The electronegativity is 2.1 for H and 3.0 for N. Based on these electronegativities, NH4 + would be expected to have polar covalent bonds with a partial positive charges on the H atoms. have polar covalent bonds with a partial negative charges on the H atoms. be ionic and contain H+ ions. be ionic and contain H- ions.

have polar covalent bonds with a partial positive charges on the H atoms. h

polar covalent or ionic.CsBr

ionic

In general, at room temperature ionic compounds are all solids and covalent compounds are all gases. ionic compounds are all solids, but covalent compounds may be solids, liquids, or gases. ionic compounds are all solids, and covalent compounds are liquids or gases. covalent compounds are all gases, but ionic compounds may be solids, liquids, or gases.

ionic compounds are all solids, but covalent compounds may be solids, liquids, or gases.

The normal boiling point for H2Te is higher than the normal boiling point for H2Se. This can be explained by larger dispersion forces for H2Te. larger dipole-dipole forces for H2Te. larger hydrogen-bond forces for H2Te. larger dipole-dipole forces, larger dispersion forces, and larger hydrogen-bond forces for H2Te.

larger dispersion forces for H2Te.

Which of the following best describes CO2? It has a molecular geometry that is linear molecular shape with no lone pairs on the I atom. linear molecular shape with lone pairs on the I atom. non-linear molecular shape with no lone pairs on the I atom. non-linear molecular shape with lone pairs on the I atom.

linear molecular shape with no lone pairs on the I atom.

Which of the following best describes CO2? It has a molecular geometry that is non-linear molecular shape with no lone pairs on the I atom. linear molecular shape with lone pairs on the I atom. non-linear molecular shape with lone pairs on the I atom. linear molecular shape with no lone pairs on the I atom

linear molecular shape with no lone pairs on the I atom.

Which of the following best describes ClF2−? It has a molecular geometry that is nonlinear with lone pairs on the Cl atom. nonlinear with no lone pairs on the Cl atom. linear with lone pairs on the Cl atom. linear with no lone pairs on the Cl atom

linear with lone pairs on the Cl atom.

The paramagnetism of O2 is explained by resonance. coordinate covalent bonding. molecular orbital theory. valence bond theory.

molecular orbital theory.

Which of the following are allowed resonance forms of NCS-? I [:N≡C−..S..:]− and [..:N=C=..S:]− II [:N≡C−..S..:]− and [:N≡C=..S:]− III [:N≡C−..S..:]− and [..:S..−C≡N:]

only 1

Which of the following should be nonplanar? only I only II only III I and III

only 3

polar covalent or ionic. CH4

polar covalent

polar covalent or ionic. SiCl4

polar covalent

polar covalent or ionic.FeBr3

polar covalent

What is the molecular geometry of SCl4? square planar seesaw tetrahedral square pyramidal

seesaw

What is the molecular geometry of SeCl4? tetrahedral square pyramidal square planar seesaw

seesaw

What is the molecular geometry of TeBr4? seesaw square planar square pyramidal tetrahedral

seesaw

Covalent bonding is a loss of electrons. gain of electrons. sharing of electrons. transfer of electrons.

sharing of electrons.

Which orbital hybridization is associated with a tetrahedral cloud arrangement? sp3 sp4 sp sp2

sp3

Which orbital hybridization is associated with a tetrahedral cloud arrangement? sp3 sp4 sp2 sp

sp3

At the equilibrium bond length the attractive forces holding the atoms together are less than the repulsive forces. the repulsive forces are greater than the attractive forces holding the atoms together. the potential energy is a maximum. the potential energy is a minimum.

the potential energy is a minimum.

NO2- is be expected to have one single and one double bond. two identical bonds intermediate between a single and a double bond. two double bonds. two single bonds.

two identical bonds intermediate between a single and a double bond.

A triple bond is generally composed of one π bond and two σ bonds. three σ bonds. two π bonds and one σ bond. three π bonds.

two π bonds and one σ bond.

What is the formal charge of P in PF4−? 0 +2 +1 −1

−1