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1 . An electron in a hydrogen atom makes a transition from the n=5 energy state

ID: 1303861 • Letter: 1

Question

1. An electron in a hydrogen atom makes a transition from the n=5 energy state to the ground state (n=1). What is the frequency of the emitted photon? _______ Hz

2. How much energy is needed to ionize a hydrogen atom in the n = 3 state? _________ eV

3. What minimum accelerating voltage would be required to produce an x-ray with a wavelength of 0.035 nm? ________ Volts

4. A doubly ionized lithium atom (Li2+) has only one electron in orbit about the nucleus. What is the radius of the ion when it is in the n = 6 excited state?
________ m

just the answers please, make sure they are correct!

Explanation / Answer

h = pnlks constant = 4.136 x10-15    e v s

E1 = energy released = 13.6( 1-1/52) = 13.6 *24/25 ev = 13.056 ev

F = frequency = E1/h = 13.056/(4.136 x10-15) = 3.15 x10 15   HZ

2)   E = energy required = 13.6/32 = 1.51 ev

3)   V = hc/(e lemda) = (4.136 x10-15 x 3x 108) /(0.035) = 35.45 kV

4) Z = number of proton = 3 ,

   ao = radius of hydrogen atom for lowest orbit = 53 x10-12 m

    n = 6

R = radius = n2 *ao /z = 36x 53 x10-12 / 3 = 0.636 x10-9 m