Deck 1: Atoms and Molecules; Orbitals and Bonding

Question 1

Indicate which of the species shown are expected to have a net dipole moment.

A)
B)
C)
D)
E)

Answer 1

Question 2

Which of the following statements about atomic orbitals is false?

A) A 1 s orbital is spherically symmetrical.
B) An atomic orbital may contain zero, one, or two electrons.
C) A 2s orbital and a 2p orbital are equal in energy.
D) A 2p_x orbital and a 2p_y orbital are equal in energy.
E) A 2 p orbital is not spherically symmetrical.

Answer 2

A 2s orbital and a 2p orbital are equal in energy.

Question 3

Which of the following molecules has a net dipole moment?

A)
B)
C)
D)
E)

Answer 3

Question 4

What is the total number of occupied p orbitals in a neutral phosphorus atom?

A)2
B)3
C)6
D)9
E)12

Question 5

Which of the following statements accurately describes the node(s) in a 2 p orbital?

A) There are zero nodes in a 2 p orbital.
B) A 2 p orbital has one spherical node.
C) A 2 p orbital has one nodal plane.
D) A 2 p orbital has one spherical node and one nodal plane.
E) A 2 p orbital has two spherical nodes.

Question 6

In which of the following Lewis structures does the nitrogen atom have a formal charge of 1+?

A)
B)
C)
D)
E)

Question 7

Which of the following Lewis structures shows an incorrectly drawn bond dipole?

A)
B)
C)
D)
E)

Question 8

Which of the following structures is the best Lewis structure for hypochlorous acid, HOCl?

A)
B)
C)
D)
E)

Question 9

Which of the following resonance forms would be expected to be the most important contributor for the anionic species?

A)
B)
C)
D)
E)

Question 10

Which of the Lewis structures shown below is incorrect?

A)
B)
C)
D)
E)

Question 11

Which one of the following sets of quantum numbers is impossible?

A) n=1, l=0, m_l=0, s=+1 / 2
B) n=1, l=1, m_l=0, s=+1 / 2
C) n=2, l=1, m_l=1, s=+1 / 2
D) n=2, l=1, m_l=-1, s=-1 / 2
E) n=3, l=0, m_l=0, s=-1 / 2

Question 12

Which of the following Lewis structures contains an oxygen atom with a 1+ formal charge?

A)
B)
C)
D)
E)

Question 13

Which of the following statements accurately describes the node(s) in a 2 s orbital?

A) There are zero nodes in a 2 s orbital.
B) A 2 s orbital has one spherical node.
C) A 2 s orbital has one nodal plane.
D) A 2 s orbital has one spherical node and one nodal plane.
E) A 2 s orbital has two spherical nodes.

Question 14

In which of the following structures does the carbon atom have a formal charge that is not zero?

A)
B)
C)
D)
E) Both c and d

Question 15

Which of the following arrow conventions is used to show the relationship of two chemical species as resonance structures?

A)
B)
C)
D)
E)

Question 16

Which of the following statements is true?

A)Ionization potential decreases going across a row left to right.
B)Ionization potential increases going down a group.
C)Electron affinity increases going across a row left to right.
D)Electron affinity increases going down a group.
E)Atoms with high ionization potentials have correspondingly high electron affinities.

Question 17

d-orbitals have two nodal planes. How many spherical nodes will a 5 d orbital contain?

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

Question 18

The rule or principle that states that the electronic state with the greatest number of unpaired spins will have the lowest energy is called

A)the Pauli principle
B)the aufbau principle
C)the Heisenberg uncertainty principle
D)Hund's rule
E)the octet rule

Question 19

What is the formal charge on the oxygen atom in each of the following Lewis structures?

A) A: 0, B: 1-, C: 1+
B) A: 1+, B: 1-, C: 0
C) A: 1-, B: 1+, C: 0
D) A: 1-, B: 1-, C: 1-
E) A: 1+, B: 1+, C: 1-

Question 20

Which of these sets of quantum numbers would define an electron in the 5d subshell?

A) n=5 ; l=2, m_l=-3, s=1 / 2
B) n=5 ; l=2, m_l=-2, s=1 / 2
C) n=5 ; l=4, m_l=-2, s=-1 / 2
D) n=5 ; l=2, m_l=-2, s=1
E) n=5 ; l=1, m_l=0, s=-1 / 2

Question 21

Which of the following statements about the molecular orbital diagram for H^2- is false?

A) There are two atomic orbitals that mix to produce molecular orbitals.
B) There is one bonding molecular orbital.
C) There is one antibonding molecular orbital.
D) All bonding orbitals are occupied.
E) All antibonding orbitals are unoccupied.

Question 22

Which of the following pairs are related as resonance structures? All nonzero formal charges are shown.

A)
B)
C)
D)
E)

Question 23

How many antibonding molecular orbitals are generated from combining one 2 p orbital on nitrogen and one 2 p orbital on carbon?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 24

Which two of the following structures are equivalent resonance contributors?

A) A and B
B) A and C
C) B and C
D) A and D
E) All the structures are equivalent.

Question 25

Which of the following molecular orbitals is the highest in energy? (All were generated by the mixing of four 2p orbitals.)

A)
B)
C)
D)
E) All four orbitals shown are equal in energy.

Question 26

A certain orbital interaction diagram has four bonding molecular orbitals and four antibonding molecular orbitals. How many atomic orbitals were mixed to create all these orbitals?

A) 2
B) 4
C) 8
D) 16
E) It cannot be determined from the information given.

Question 27

In the orbital interaction diagram for ground state H₂, how many electrons occupy the antibonding molecular orbital?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 28

Which of the structures shown is not related to Structure A as a resonance contributor?

A)
B)
C)
D)
E)

Question 29

Explain what is meant by the term quantized as it applies to the energy of an electron.

Question 30

Define the term node as it applies to an orbital.

Question 31

Which of the following pairs are not related as resonance structures?

A)
B)
C)
D)
E)

Question 32

What is the relationship between the principal quantum number n and the number of nodes in an orbital?

Question 33

Which of the following statements is true about Lewis acids and bases?

A)Lewis acids are also called nucleophiles.
B)A Lewis base always accepts a proton from a Lewis acid.
C)The interaction between a Lewis acid and a Lewis base leads to a covalent bond.
D)A Lewis base accepts an electron pair from a Lewis acid.
E)Homolytic bond cleavage leads to the formation of a Lewis acid/base pair.

Question 34

A student wrote the following electron configuration for a ground state, neutral nitrogen atom: Explain why the configuration does not describe the lowest energy state of a ground-state nitrogen atom and provide the lowest-energy electron configuration for nitrogen.

Question 35

Which of these orbital interactions would be expected to form a covalent bond with the highest BDE?

A) H atom 1 s with H⁺cation 1 s
B) He atom 1 s with He atom 1 s
C) He atom 1 s with H atom 1 s
D)H⁺cation 1 s with He⁺ cation 1 s
E) H⁺cation 1 s with He atom 1 s

Question 36

How many molecular orbitals are generated from combining one 2 p orbital on carbon and one 2 p orbital on oxygen?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 37

How many values can m_l have for quantum number l=5 ?

Question 38

Write the lowest-energy electron configuration for a neutral, ground-state oxygen atom.

Question 39

Each of the chemical events shown represents a mechanistic step in a reaction you will learn this semester.Which of the following pictures represents the heterolytic cleavage of a carbon-oxygen
Bond?

A)
B)
C)
D)
E)

Question 40

State the Heisenberg uncertainty principle.

Question 41

Draw a Lewis structure for methyl anion, -CH₃.

Question 42

Is forming a bond between an oxygen atom and a hydrogen atom endothermic or exothermic? Briefly explain your answer.

Question 43

For each molecule shown, indicate whether the molecule is polar by drawing a dipole arrow pointing towards the negative end of the molecule.

Question 44

The carbon-nitrogen bond in formamide, HCONH₂, has been shown to have a bond length that is in between a typical C-N single bond and a typical C-N double bond. Provide an explanation to account for this observation, using relevant structures as support.

Question 45

The Lewis structure of the anion shown has an additional resonance structure that is a more important representation for this anion.Draw the better resonance contributor, using curved arrow formalism to show how the new structure is obtained from the original structure.

Question 46

Using curved arrow formalism, show the homolytic cleavage of the O-O bond in dimethyl peroxide. Draw the products of the reaction, including all lone pairs and unpaired electrons.

Question 47

Use an orbital interaction diagram to provide an explanation for the fact that diatomic helium, He₂, does not exist.

Question 48

Draw Lewis structures for the following compounds.Show all nonbonding electrons and indicate the formal charge on any atom that has a nonzero charge.

Question 49

Beryllium hydride (BeH₂) is a linear molecule with two perpendicular p-orbitals on the beryllium atom:

An s-orbital approaching BeH₂ will only be able to interact with one of the two p-orbitals; explain why.

Question 50

In the orbital interaction diagram for H₂ shown here, label the atomic orbitals, the bonding molecular orbital, and the antibonding molecular orbital.

Question 51

Which of the following resonance structures is the least important contributor to the resonance hybrid, and why?

Question 52

Draw a Lewis structure for methyl cation, ⁺CH₃.

Question 53

Using the Lewis structure of acetaldehyde shown, draw an additional reasonable resonance contributor.Show the conversion of the original structure to your new structure using curved arrow formalism.Include all lone pairs of electrons and nonzero formal charges in the new
structure.

Question 54

Draw a Lewis structure for acetamide, CH₃CONH₂.

Question 55

Use the bond dissociation energies given to estimate the enthalpy change, ΔH°, of the following reaction.

Bond dissociation energies (kcal/mol): C-O, 92; H-Br, 88; O-H, 119; C-Br, 72.

Question 56

The Lewis structure shown has an additional resonance contributor.Draw this contributor and determine which structure is a better contributor to the resonance hybrid.Provide a brief
explanation for your choice.

Question 57

Draw an orbital interaction diagram for a pair of 2 p orbitals interacting in a side-by-side manner. Draw the atomic orbitals and the bonding and antibonding molecular orbitals and indicate the relative energy levels of all orbitals.

Question 58

A molecule called boron trifluoride etherate has the formula BF₃O(CH₂CH₃)₂. Draw a Lewis structure for this molecule, including all nonzero formal charges and lone pairs of electrons.

Question 59

Draw a resonance form for each of the following species that would be expected to be a better contributor.Use curved arrows to show the "movement" of electrons and double-headed arrows between the resonance structures.

Question 60

Applying the aufbau principle and Hund's rule, construct the electronic configuration of the element nitrogen.

Question 61

The reaction shown here is an example of one you will learn later in the course.Identify the Lewis acid and the Lewis base in the reaction.

Question 62

Identify the nucleophile and the electrophile in the following reaction and draw the product of the reaction.

Question 63

Define the term Lewis base.

Question 64

Draw a molecular orbital diagram showing the formation of a sigma-bond between the vacant 2p orbital on boron in BH₃ and the filled 1s orbital of the hydride anion to form the borohydride anion: