Deck 8: Covalent Bonding

Question 1

Which statement about drawing Lewis dot structures is incorrect?

A) The element boron has three electrons in its Lewis symbol.
B) One must subtract electrons to form a cation from a neutral atom.
C) One must add electrons to form an anion from a neutral atom.
D) Not every element obeys the octet rule.
E) Second period elements can exceed the octet rule.

Answer 1

Second period elements can exceed the octet rule.

Question 2

Which statement concerning the interaction between two atoms is incorrect?

A) If two atoms are widely separated, there is very little attraction between them.
B) When two atoms are one bond length apart, the electrons on one atom are attracted to the nucleus of the other atom.
C) When two atoms have very little separation between them, repulsion occurs.
D) A covalent bond occurs when electrons are shared between the bonded atoms.
E) As atoms get closer together, their electrons attract each other.

Answer 2

As atoms get closer together, their electrons attract each other.

Question 3

Which molecule does not contain a double bond?

A) CO₂
B) CH₂O
C) O₂
D) HCOOH
E) HCN

Answer 3

HCN

Question 4

List these compounds in order of decreasing number of valence electrons: CO₂, CH₃Cl, HCN.

A) CH₃Cl, HCN, CO₂
B) CO₂, HCN, CH₃Cl
C) CH₃Cl, CO₂, HCN
D) CO₂, CH₃Cl, HCN
E) HCN, CO₂, CH₃Cl

Question 5

Which statement about covalent bonds is false?

A) Covalent bonds allow atoms to achieve a filled outermost electron shell.
B) Covalent bonds are unreactive.
C) Covalent bonds occur in molecular compounds.
D) Covalent bonds involve valence electrons.
E) Covalent bonds form between non-metal atoms.

Question 6

How many electrons will be in the correctly drawn Lewis Structure for CCl₄?

A) 32
B) 74
C) 35
D) 8
E) 11

Question 7

Which element has five electrons in its Lewis symbol?

A) argon
B) boron
C) carbon
D) phosphorus
E) sulfur

Question 8

Which element has four electrons in its Lewis symbol?

A) aluminum
B) beryllium
C) carbon
D) magnesium
E) oxygen

Question 9

Which molecule contains a double bond?

A) HCN
B) H₂S
C) C₂H₂
D) C₂H₆
E) O₂

Question 10

How many electrons will be in the correctly drawn Lewis Structure for ?

A) 20
B) 22
C) 24
D) 26
E) 30

Question 11

Write the correct Lewis dot structure for N₂. Which statement correctly describes the structure?

A) The structure contains 1 single bond 5 lone electron pairs.
B) The structure contains 1 double bond and 4 lone electron pairs.
C) The structure contains 1 double bond and 5 lone electron pairs.
D) The structure contains 1 double bond and 6 lone electron pairs.
E) The structure contains 1 triple bond and 2 lone electron pairs.

Question 12

Write the correct Lewis dot structure for CCl₂O. Which statement correctly describes the structure?

A) The structure contains 3 single bonds, 1 double bond, and 2 lone electron pairs.
B) The structure contains 3 single bonds, 1 triple bond, and 8 lone electron pairs.
C) The structure contains 2 single bonds, 1 double bond, and 2 lone electron pairs.
D) The structure contains 2 single bonds, 1 double bond and 8 lone electron pairs.
E) The structure contains 1 single bond, 1 triple bond, and 2 lone electron pairs.

Question 13

How many electrons are shown in the correctly drawn Lewis Structure for CH₃CH₃?

A) 8
B) 10
C) 14
D) 18
E) 34

Question 14

Assume all hydrocarbons given are linear. Which compound will contain one double bond?

A) C₃H₆
B) C₆H₁₀
C) C₂H₂
D) CH₄
E) C₅H₁₂

Question 15

Write the correct Lewis dot structure for O₂. Which statement correctly describes the structure of the molecule?

A) There is one double bond and four lone electron pairs.
B) There is one double bond and six lone electron pairs.
C) There is one single bond and four lone electron pairs.
D) There is one single bond and six lone electron pairs.
E) There is one single bond, one double bond, and six lone electron pairs.

Question 16

Which molecule does not contain a multiple bond?

A) H₂O₂
B) C₂H₂
C) CH₂O
D) CO₂
E) O₂

Question 17

Select the element that never forms more than one bond in a Lewis dot structure.

A) O
B) C
C) N
D) Al
E) H

Question 18

Determine the number of electrons required by these four elements, in the order listed, to achieve an octet of electrons.

A) 1 3 2 4
B) 3 4 2 2
C) 3 2 4 1
D) 4 3 5 2
E) 5 6 4 7

Question 19

Which molecule contains a triple bond?

A) C₂H₄
B) CCl₄
C) H₂O
D) N₂
E) O₂

Question 20

Assume all hydrocarbons given are linear. Which compound will contain one triple bond?

A) C₃H₆
B) C₈H₁₈
C) C₄H₈
D) CH₄
E) C₇H₁₂

Question 21

Predict the relative bond lengths of the four single bonds given below and arrange them from shortest to longest:

A) N-C < N-Si < N-I < N-H
B) N-H < N-C < N-Si < N-I
C) N-I < N-Si < N-H < N-C
D) N-Si < N-I < N-C < NH
E) N-H < N-Si < N-C < N-I

Question 22

Which statement about bond energies is false?

A) A carbon-carbon multiple bond requires less energy to break than a carbon-carbon single bond.
B) The carbon-carbon bonds in an alkane have very similar bond energies.
C) It is assumed that a carbon-hydrogen bond has the same bond energy whether it is found in an alcohol or an alkane.
D) The formation of a carbon-oxygen double bond from the unbonded atoms yields more energy than the formation of a carbon-oxygen single bond from the unbonded atoms.
E) Bond energy calculations require no knowledge of the bond polarity but they do require knowledge of the bond multiplicity and the average bond energies.

Question 23

Which of the following compound can exhibit cis-trans isomerism?

A) CH₂=CH₂
B) CH₃CH₃
C) H₂C=O
D) ClHC=CHCl
E) Cl₂C=CH₂

Question 24

Which bond is least polar?

A) C-C
B) C-N
C) N-H
D) C-F
E) C-O

Question 25

Which bond is longest?

A) C-O
B) C-P
C) C-H
D) C-C
E) C-N

Question 26

Assume all hydrocarbons given are linear. Which compound will contain no multiple bonds?

A) C₂H₄
B) C₃H₄
C) C₆H₁₄
D) C₈H₁₆
E) C₉H₁₈

Question 27

Which bond is strongest?

A) carbon-nitrogen triple bond
B) carbon-nitrogen double bond
C) carbon-hydrogen single bond
D) carbon-carbon triple bond
E) carbon-carbon single bond

Question 28

Which represents a non-polar covalent bond?

A) H-O
B) C-N
C) C-C
D) Li-F
E) S-O

Question 29

Determine the formula for an alkyne, alkene and alkane, in this order, containing 3 carbons.

A) C₃H₃ C₃H₆ C₃H₄
B) C₃H₆ C₃H₈ C₃H₁₀
C) C₃H₄ C₃H₈ C₃H₆
D) C₃H₄ C₃H₆ C₃H₈
E) C₃H₆ C₃H₁₀ C₃H₈

Question 30

From the data below, calculate the approximate enthalpy change of reaction for the reaction below.

A) -392 kJ
B) -219 kJ
C) -128 kJ
D) 219 kJ
E) 392 kJ

Question 31

Which bond is shortest?

A) carbon-oxygen double bond
B) carbon-oxygen single bond
C) carbon-nitrogen single bond
D) carbon-carbon double bond
E) carbon-nitrogen double bond

Question 32

Write the correct Lewis dot structures for the compounds given below. Arrange them in order of shortest to longest bond lengths. Consider only the carbon-carbon and carbon-oxygen bonds.

A) C₂H₆ < C₂H₄ < C₂H₂ < CO
B) C₂H₂ < CO < C₂H₄ < C₂H₆
C) C₂H₂ < C₂H₄ < C₂H₆ < CO
D) CO < C₂H₂ < C₂H₄ < C₂H₆
E) CO < C₂H₆ < C₂H₄ < C₂H₂

Question 33

From the data given below, calculate the approximate enthalpy change of reaction for the reaction below.

A) -490 kJ
B) -276 kJ
C) -138 kJ
D) +138 kJ
E) +325 kJ

Question 34

In organic compounds, cis-trans isomerism is associated with which types of bonds?

A) carbon-carbon triple bonds
B) carbon-carbon single bonds
C) carbon-carbon double bonds
D) carbon-oxygen single bonds
E) carbon-oxygen double bonds

Question 35

Predict qualitatively the relative bond lengths of the four single bonds given below and arrange them from shortest to longest:

A) C-C < N-N < O-O < F-F
B) N-N < O-O < F-F < C-C
C) F-F < O-O < N-N < C-C
D) O-O < N-N < F-F < C-C
E) C-C < F-F < N-N < O-O

Question 36

Which bond is longest?

A) C-O
B) C-I
C) C-Br
D) C-C
E) C-N

Question 37

Which element is the most electronegative?

A) phosphorus
B) silicon
C) carbon
D) nitrogen
E) oxygen

Question 38

Which statement about cis and trans isomers is false? The cis- and trans- isomers of a compound:

A) Have the same chemical formulas
B) Have the same molecular weights.
C) Occur in compounds containing triple bonds.
D) Have different boiling points.
E) Have different melting points.

Question 39

Which bond is shortest?

A) carbon-oxygen single bond
B) carbon-hydrogen single bond
C) hydrogen-hydrogen single bond
D) carbon-carbon double bond
E) carbon-oxygen triple bond

Question 40

From the data below, calculate the approximate enthalpy change for the reaction below.

A) -806 kJ
B) -98 kJ
C) 98 kJ
D) 120 kJ
E) 806 kJ

Question 41

Which statements about resonance are true?
I. Resonance hybrids do occur because a compound changes back and forth between two or more resonance structures.
II. Resonance structures do differ in the arrangement of electrons but not in the arrangement of atoms.
III. Resonance hybrids contain delocalized electrons.
IV. Resonance structures for a given compound always contribute equally to the resonance hybrid.
V. Resonance structures occur when there are two or more valid Lewis structures for a given compound.
VI. Resonance hybrids are a composite of resonance structures.

A) I, II, V, VI
B) II, III, IV, VI
C) II, IV, V, VI
D) II, III, V, VI

Question 42

Write the singly bonded Lewis dot structure for BF₃. Which statement best describes this structure?

A) The octet rule is obeyed for all atoms.
B) At least one atom has less than an octet of electrons.
C) There is a lone pair of electrons on the boron atom.
D) The boron atom has a formal charge of +1.
E) At least one atom exceeds the octet rule.

Question 43

What is the formal charge on sulfur in SO₂?

A) +2
B) +1
C) 0
D) -1
E) -2

Question 44

Write the correct Lewis structure for XeF₄. This molecule exceeds the octet rule. Determine the number of bonding electron pairs and lone electron pairs that are present on the central atom.

A) 4 bonding pairs and 1 lone pair
B) 5 bonding pairs and 0 lone pairs
C) 4 bonding pairs and 2 lone pairs
D) 5 bonding pairs and 2 lone pairs
E) 6 bonding pairs and 0 lone pairs

Question 45

Which of these species does not have resonance structures?

A)
B) SO₂
C) H₂O
D)
E) O₃

Question 46

Which element is the least electronegative?

A) calcium
B) cesium
C) iron
D) barium
E) potassium

Question 47

How many resonance forms will ozone, O₃, have?

A) -1
B) 0
C) 1
D) 2
E) 3

Question 48

Which of these species has one or more resonance structures?

A) H₂S
B) CCl₄
C) PCl₃
D)
E)

Question 49

Construct correct Lewis dot structures for the three molecules below. Determine which compound(s) exceed the octet rule.

A) I
B) II
C) III
D) II and III
E) I, II, and II

Question 50

Write the correct Lewis structure for AsCl₅. This molecule exceeds the octet rule. Determine the number of bonding electron pairs and lone electron pairs that are present on the central atom.

A) 5 bonding pairs and 0 lone pairs
B) 5 bonding pairs and 1 lone pair
C) 5 bonding pairs and 2 lone pairs
D) 6 bonding pairs and 0 lone pairs
E) 6 bonding pairs and 1 lone pair

Question 51

Which of these elements cannot exceed the octet rule?

A) Si, P, S, Cl
B) B, N, O, F
C) O, S, F, Cl
D) B, Si, N, P
E) All eight elements can exceed the octet rule.

Question 52

The correctly drawn Lewis dot structure for linear H₂CO₂ contains _____________ lone electron pairs, _____________ single bonds and _____________ double bonds.

Question 53

Which statement about molecular orbital theory is false?

A) Molecular orbitals are derived from valence atomic orbitals.
B) Each molecular orbital can hold two electrons.
C) Molecular orbitals hold valence electrons.
D) Molecular orbital theory is a model of covalent bonding.
E) Molecular orbitals only occur as bonding orbitals.

Question 54

Which statement properly describes the formal charges on the atoms in ?

A) -2 on oxygen, +5 on phosphorus
B) -1 on oxygen, +4 on phosphorus
C) -1 on oxygen, +1 on phosphorus
D) +1 on oxygen, -1 on phosphorus
E) +1 on oxygen, -3 on phosphorus

Question 55

What is the formal charge on carbon in CO?

A) -2
B) -1
C) 0
D) +1
E) +2

Question 56

Which statement properly describes the formal charges on the atoms in ?

A) +2 on sulfur, -2 on oxygen
B) +2 on sulfur, -1 on oxygen
C) +1 on sulfur, -1 on oxygen
D) -1 on sulfur, +2 on oxygen
E) -2 on sulfur, 0 on oxygen

Question 57

What is the formal charge on carbon in HCN?

A) -2
B) -1
C) 0
D) +1
E) +2

Question 58

Which element is the most electronegative?

A) sulfur
B) iodine
C) nitrogen
D) aluminum
E) carbon

Question 59

Hydrocarbons that contain double bonds are called _____________.

Question 60

In a polar covalent bond, _____________ are _____________ shared.

Question 62

An element is allowed to have an expanded octet if empty _____________ are available.

Question 63

Oxygen atoms contribute _____________ electrons to a Lewis Dot structure.

Question 64

The ____________ of an element is its ability to pull electrons towards itself when participating in a covalent bond.

Question 65

Hydrocarbons with only single bonds are called _____________.

Question 66

The cyanide ion, CN^-, has a(n) ____________ of -1 on the carbon and 0 on the nitrogen.

Question 67

Match the following:

Question 68

Benzene is an example of a resonance hybrid because it contains _____________ electrons.