# CHEM 132B Study Guide - Quiz Guide: Spherical Harmonics, Term Symbol, Haplogroup R2AExam

by OC3523515

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**preview**shows page 1. to view the full**5 pages of the document.**Chem 132B Practice Quiz 2 Key

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Problem 1

Encircle all that are true regarding the spherical harmonic wavefunctions.

a) The energy associated with the spherical harmonic wavefunctions is inde-

pendent of the quantum number ml.True

b) The magnitude of orbital angular momentum is not quantized, but its

projection onto a chosen axis is. False

c) If we determine the angular momentum of the spherical harmonic wave-

function along x, then its projections along zand yare unknown. True

d) We cannot both determine the magnitude of orbital angular momentum

and its projection onto the z-axis at the same time. False

Problem 2

Encircle all that are true.

a) The groundstate of hydrogen is 2S0.False

b) The groundstate of helium is 1S0.True

c) The groundstate of He+is 2S1/2.True

d) The groundstate of H−is 2P1/2.False

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Problem 3

An excited hydrogen atom is the 2s1conﬁguration.

a) Give an expression for

1) the radial part of the wavefunction (Rn,l(r)).

2) the angular part of the wavefunction (Yl,ml(θ, φ)).

•R2,0(r) = 1

√8Z

a03/2(2 −r/a0)e−r/2a0

•Y0,0(θ, φ) = 1

4π1/2

b) Determine the location (r > 0) along rwhere there is zero probability of

ﬁnding the electron (in units of a0).

Radial node is found when R2,0(r) = 0, which is when (2 −r/a0) = 0.

This gives r= 2a0

c) Give the term symbol of the 2s1conﬁguration.

l= 0, s =1

2, j =1

2, which gives 2S1/2

d) Can the atom decay to the ground state through the emission of a photon?

No, ∆l6=±1.

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