(a) Construct the spatial wave function (ψ)for hydrogen in the state n=3,I=2,m=1.Express your answer as a function of r,θ,ϕ,anda(the Bohr radius) only—no other variables (p,z,etc.) or functions (p,v,etc.), or constants (A,c0,etc.), or derivatives, allowed (π is okay, and e, and 2, etc.).

(b) Check that this wave function is properly normalized, by carrying out the appropriate integrals over, θ,andϕ.

(c) Find the expectation value of rsin this state. For what range of s (positive and negative) is the result finite?

Short Answer

Expert verified

(a)ψ321=R32Y21=-1π181a7/2r2e-r/3asinθcosθe.

(b)The wave function is properly normalized by 1

(C)rs=-7.

Step by step solution

01

(a) Constructing the spatial wave function for hydrogen.

ψ321=R32Y21=481301a3/2ra2e-r/3a-158πsinθcosθe=-1π181a7/2r2e-r/3asinθcosθe.

02

 Step2: (b) Checking the wave function is properly normalized.

ψ2d3r=1π1π812a7r4e-2r/3asin2θcos2θr2sinθdrdθdϕ.=1π812a72π0r6e-2r/3adr0π1-cos2θcos2θcos2θdθ.=2812a76!3a27-cos3θ3+cos5θ50π.=238a76.5.4.3.237a72723-25=3.54.415=1.

03

 Step3: (c)Finding the exceptional value of rs

rs=0rsR322r2dr=48121301a70rs+6e-2r/3adr.=815812a7s+6!3a2s+7=s+6!3a251720=(s+6)!6!3a23.FiniteforS>-7.

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Most popular questions from this chapter

Determine the commutator of S2withSZ(1)(whereSS(1)+S(2)) Generalize your result to show that

[S2,S1]=2Ih(S1×S2)

Comment: Because Sz(1)does not commute with S2, we cannot hope to find states that are simultaneous eigenvectors of both. In order to form eigenstates ofS2weneed linear combinations of eigenstates ofSz(1). This is precisely what the Clebsch-Gordan coefficients (in Equation 4.185) do for us, On the other hand, it follows by obvious inference from Equation 4.187that the sumrole="math" localid="1655980965321" S(1)+S(2)does commute withdata-custom-editor="chemistry" S2, which is a special case of something we already knew (see Equation 4.103).

Show thatΘ=AIn[tan(θ2)]satisfies the θequation (Equation 4.25), for l = m = 0. This is the unacceptable "second solution" -- whats wrong with it?

An electron is in the spin state

x=A(1-2i2)

(a) Determine the constant by normalizing x.

(b) If you measured Szon this electron, what values could you get, and what is the probability of each? What is the expectation value of Sz?

(c) If you measured Sxon this electron, what values could you get, and what is the probability of each? What is the expectation value of Sx?

(d) If you measured Syon this electron, what values could you get, and what is the probability of each? What is the expectation value ofSy?

Work out the spin matrices for arbitrary spin , generalizing spin (Equations 4.145 and 4.147), spin 1 (Problem 4.31), and spin (Problem 4.52). Answer:

Sz=(s0000s-10000s-200000-s)Sx=2(0bs0000bs0bs-10000bs-10bs-20000bs-200000000b-s+10000b-s+10)Sy=2(0-ibs0000ibs0-ibs-10000-ibs-10-ibs-20000-ibs-200000000-ibs+10000-ibs+10)

where,bj(s+j)(s+1-j)

An electron is in the spin state

χ=A3i4

(a) Determine the normalization constant .

(b) Find the expectation values of Sx,Sy , and Sz.

(c) Find the "uncertainties" ,σSx , σSyandσSz . (Note: These sigmas are standard deviations, not Pauli matrices!)

(d) Confirm that your results are consistent with all three uncertainty principles (Equation 4.100 and its cyclic permutations - only with in place ofL, of course).

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