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Electrons in Atoms and Molecules

Test 1

Chemistry 308

Spring 2014

4) What is the frequency of a helium-neon laser light with a wavelength of 632.8 nm? The speed

of light is 3.00 × 108 m/s.

A) 4.74 × 1014 s-1

B) 4.74 × 105 s-1

C) 2.11 × 10-15 s-1

D) 1.58 × 10-15 s-1

Topic: Section 3.1 Light and the Electromagnetic Spectrum

12) What is the de Broglie wavelength of an electron (m = 9.11 × 10-31 kg) moving at a velocity

of 3.0 × 107 m/s (10% of the speed of light)?

A) less than 3.9 × 10-12 m

B) 2.4 × 10-11 m

C) 3.3 × 10-8 m

D) greater than 1.1 × 10-4 m

Topic: Section 3.4 Wavelike Properties of Matter

22) For an electron in a given atom, the larger n, the

A) larger the average distance from the nucleus and the higher the orbital energy.

B) larger the average distance from the nucleus and the lower the orbital energy.

C) smaller the average distance from the nucleus and the higher the orbital energy.

D) smaller the average distance from the nucleus and the lower the orbital energy.

Topic: Section 3.6 Wave Functions and Quantum Numbers

27) The number of orbitals in a given subshell, such as the 5d subshell, is determined by the

number of possible values of

A) n.

B) l.

C) ml.

D) ms.


30) How many electrons can a single orbital hold?

A) 2n

B) 2

C) 2l + 1

D) 8


37) For an orbital, a node is

A) the midpoint of the orbital.

B) a surface inside which there is a 90% chance of finding the electron.

C) a surface where there is a maximum probability of finding the electron.

D) a surface where there is no chance of finding the electron.

Topic: Section 3.7 The Shapes of Orbitals

39) Which of the following is true? The probability density

A) for all s orbitals is independent of direction from the nucleus.

B) for all s orbitals is independent of distance from the nucleus.

C) is independent of direction from the nucleus for 1s orbitals only.

D) is independent of distance from the nucleus for 1s orbitals only.

Topic: Section 3.7 The Shapes of Orbitals

42) What is the first ionization energy for a hydrogen atom in the ground state? The Rydberg

constant is 1.097 × 10-2 nm-1

A) 7.27 × 10-36 J

B) 1.63 × 10-27 J

C) 2.18 × 10-18 J

D) 0.00823 J

Topic: Section 3.8 Quantum Mechanics and Atomic Line Spectra

58) What is the ground-state electron configuration of Co?

A) [Ar]3d9

B) [Ar]4s13d8

C) [Ar]4s23d7

D) [Ar]4s24p64d1

Topic: Section 3.13 Electron Configurations and the Periodic Table

Use orbital diagrams for questions below, 77-80.

77) Which of the above fourth-shell orbitals is a 4pz orbital?

A) orbital (a)

B) orbital (b)

C) orbital (c)

D) orbital (d)

Topic: Key Concept Problems

78) Which of the above fourth-shell orbitals is a 4py orbital?

A) orbital (a)

B) orbital (b)

C) orbital (c)

D) orbital (d)


79) Which of the above fourth-shell orbitals is a 4dx2-y2 orbital?

A) orbital (a)

B) orbital (b)

C) orbital (c)

D) orbital (d)


80) Which of the above fourth-shell orbitals is a 4dyz orbital?

A) orbital (a)

B) orbital (b)

C) orbital (c)

D) orbital (d)


81) For the fourth-shell orbital shown below, what are the principal quantum number, n, and the

angular momentum quantum number, l?

A) n = 4 and l = 0

B) n = 4 and l = 1

C) n = 4 and l = 2

D) n = 4 and l = 3


101) Which orbital-filling diagram represents the anomalous ground state of chromium?

A)

B)

C)

D)

3) Light behaves as if it were a stream of small particles, called ________, each having an

amount of energy called a ________.

Topic: Section 3.3 Particlelike Properties of Electromagnetic Energy

4) A solution to the Schrödinger wave equation is a ________, or orbital, represented by the

symbol Ψ, and the probability of finding an electron defined by Ψ within a given volume of

space around the nucleus is ________.


5) The energy of an electron in a multielectron atom depends on the quantum numbers ________

and ________.


57) How many valence shell electrons does an atom of aluminum have?

A) 1

B) 2

C) 3

D) 13

Topic: Section 4.7 The Octet Rule

64) In the reaction of sodium metal with chlorine gas which of the following processes releases

energy?

A) Cl2(g) → 2 Cl(g)

B) Cl(g) + e- → Cl-(g)

C) Na(s) → Na(g)

D) Na(g) → Na+(g) + e-

Topic: Section 4.8 Ionic Bonds and the Formation of Ionic Solids

5) Which is the longest bond?

A) N–N

B) N=N

C) N≡N

D) All three bond lengths should be about the same.

Topic: Section 5.2 Strengths of Covalent Bonds

23) Based on the indicated electronegativities, arrange the following in order of increasing ionic

character: CsBr, LaBr3, PBr3, MgBr2.

A) CsBr, LaBr3, MgBr2, PBr3

B) CsBr, MgBr2, PBr3, LaBr3

C) PBr3, LaBr3, MgBr2, CsBr

D) PBr3, MgBr2, LaBr3, CsBr

Topic: Section 5.4 Polar Covalent Bonds: Electronegativity

62) What is the O-N-O bond angle in NO3-?

A) less than 109.5°

B) 109.5°

C) 120°

D) greater than 120°

Topic: Section 5.10 Molecular Shapes: The VSEPR Model

66) What is the smallest bond angle in SF6?

A) 60°

B) 90°

C) 109.5°

D) 120°

Topic: Section 5.10 Molecular Shapes: The VSEPR Model

84) If an electron is added to H2 it would go into a

A) σ molecular orbital and strengthen the H–H bond.

B) σ molecular orbital and weaken the H–H bond.

C) σ* molecular orbital and strengthen the H–H bond.

D) σ* molecular orbital and weaken the H–H bond.

Topic: Section 5.14 Molecular Orbital Theory: The Hydrogen Molecule

86) Compare the energies of molecular orbitals of homonuclear diatomic molecules with the

energies of the atomic orbitals with which they correlate.

A) Both bonding and antibonding molecular orbitals lie lower in energy than the atomic orbitals.

B) Bonding orbitals are lower and antibonding orbitals are higher in energy than the atomic

orbitals.

C) Bonding orbitals are higher and antibonding orbitals are lower in energy than the atomic

orbitals.

D) Both bonding and antibonding molecular orbitals are higher in energy than the atomic

orbitals.

Topic: Section 5.15 Molecular Orbital Theory: Other Diatomic Molecules

87) Which molecular orbitals for homonuclear diatomic molecules are degenerate?

A) π molecular orbitals

B) σ molecular orbitals

C) π molecular orbitals and σ molecular orbitals

D) neither π molecular orbitals nor σ molecular orbitals


89) The following MO diagram is appropriate for Li2 and Be2. Based on this diagram,

A) both are stable and diamagnetic.

B) Li2 is stable and diamagnetic, but Be2 is unstable.

C) Be2 is stable and diamagnetic, but Li2 is unstable.

D) Be2 is stable and paramagnetic, but Li2 is unstable.


172) Which drawing represents a σ bonding molecular orbital for a homonuclear diatomic

molecule?

A)

B)

C)

D)


173) Which drawing represents a σ* antibonding molecular orbital for a homonuclear diatomic

molecule?

A)

B)

C)

D)


10. a. What is the meaning of the plot below that involves the hydrogen atom 1s wavefuntion,

21s, as calculated from the Schrodinger equation for the hydrogen atom? (

21s

is essentially the

same thing as (R(r)2, that is, the radial portion squared of the 1s wavefunction.

21s is the total

wavefunction; (R(r)2

is the radial portion only of the 1s wavefunction. They difference only by a

numerical constant.)

b. How is the maximum of the 1s plot related to the Bohr atom theory?

a.____________________________________________________________________________

______________________________________________________________________________

________________________

b.____________________________________________________________________________

______________________________________________________________________________

________________________

4r2

2

This maximum probability for the

1s orbital is at 0.5292 angstroms

or 1 atomic unit, a0.

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