Deck 19: Atomic Physics

Question 1

The probability density for the 1s state is given by | $\Psi$ 1s|2.The probability of finding the particle somewhere in space is:

A)
B)
C)
D)
E)

Answer 1

Question 2

In the subshell of the Li2+ ion with orbital quantum number , the allowed values of the magnetic quantum number are:

A)(- to )
B)(-( + 1) to ( + l)
C)(-( + 2) to ( + 2)
D)(-( + 3) to ( + 3)
E)0 to n -1

Answer 2

(- to )

Question 3

How fast is the electron moving in the first Bohr orbit?

A)3.3 * 106 m/s
B)2.2 * 106 m/s
C)4.4 * 106 m/s
D)5.5 *106 m/s
E)5.5 * 1015 m/s

Answer 3

2.2 * 106 m/s

Question 4

A hydrogen atom is in its first excited state (n = 2).The linear momentum of the electron is (in kg . m/s):

A)3 * 10-24
B)2 * 10-24
C)1 *10-24
D)4 * 10-24
E)3 * 10-15

Question 5

One of the main problems with the Bohr model of the hydrogen atom when compared with the results of the methods of quantum mechanics used to describe atoms, was that the Bohr model predicted:

A)the ground state angular momentum was L = 1
B)the frequency of the radiation emitted when an electron 'jumps' from one allowed orbit to another was hf = Ei - Ef.
C)the potential energy function for the hydrogen atom was given by V(r) = -ke2/r.
D)the energy of the ground state of the hydrogen atom was En =-13.6 eV.

Question 6

The allowed values of for the n = 3 shell in a Li2+ ion are:

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

Question 7

Suppose Bohr had chosen the potential energy of the electron in the hydrogen atom to be V = 0 when the electron is in the orbit with n = 1.He could do this by:

A)choosing n = 1 for the orbit where the kinetic energy of the electron is zero.
B)adding a constant 13.6 eV to the potential energy for all values of n.
C)adding a constant 27.2 eV to the potential energy for all values of n.
D)subtracting a constant 13.6 eV from the potential energy for all values of n.
E)subtracting a constant 27.2 eV from the potential energy for all values of n.

Question 8

The probability density of a particle at a distance r from the nucleus is essentially the:

A)probability of finding the particle within a small volume about r.
B)probability per unit area of finding the particle within a unit area centred on r.
C)probability per unit length of finding the particle within a unit length of r.
D)probability per unit volume of finding the particle within a small volume about r.
E)

Question 9

For the following allowed transitions, which photon would have the largest wavelength when an electron 'jumps' from one energy level, characterised by the quantum number n, to another?

A)n = 2 to n = 1
B)n = 3 to n = 2
C)n = 3 to n = 1
D)n = 1 to n = 3
E)n = 4 to n = 1

Question 10

An electron in a hydrogen atom makes a transition from the n = 3 to the n = 1 energy state.Determine the wavelength of the emitted photon (in nm).

A)1006
B)209
C)306
D)103
E)821

Question 11

An energy of 13.6 eV is needed to ionise an electron from the ground state of a hydrogen atom.Selecting the longest wavelength that will work from those given below, what wavelength is needed if a photon accomplishes this task?

A)60 nm
B)80 nm
C)70 nm
D)90 nm
E)40 nm

Question 12

The radial portion of the de Broglie wavefunction for an electron in the ground state of the hydrogen atom is $\Psi$ 1s(r) = 1/()1/2 exp(-r/a0) where a0 is the Bohr radius.The probability of finding the electron is:

A)
B)
C)
D)
E)

Question 13

In a shell of the hydrogen atom with n = 3, the permitted values of the orbital magnetic quantum number are:

A)(-1, 0, 1)
B)2, 1, 0
C)2, 1, 0, -1, -2
D)0
E)3, 2, 1, 0, -1, -2, -3

Question 14

The energy needed to remove an electron from the first excited state of a Li2+ ion is:

A)53 eV
B)31 eV
C)92 eV
D)122 eV
E)61 eV

Question 15

The K, L, M symbols represent values of the quantum number:

A)n
B)
C)
D)ms
E)mj

Question 16

The number of states in the He+ ion corresponding to the principle quantum number n = 5 are:

A)18
B)25
C)50
D)9
E)11

Question 17

Of the following states, 5s, 3p, 4f, 5p, 4g, 3d, and 2p, the one which is NOT allowed is:

A)3p
B)4f
C)3d
D)4g
E)2p

Question 18

The s, p, d, f, symbols represent values of the quantum number:

A)ms
B)n
C)
D)
E)mj

Question 19

If P(r) is the radial probability density function for an electron in the ground state of a hydrogen atom, the most probable value for r can be found from:

A)dP/dt
B)dP/dr
C)
D)
E)d2P/dr2

Question 20

The energy needed to change a He+ ion in the ground state into a He2+ ion is:

A)13.6 eV
B)54.4 eV
C)112.4 eV
D)92.9 eV
E)27.2 eV

Question 21

In 1921, Stern and Gerlach performed an experiment that first demonstrated:

A)orbital angular momentum quantisation.
B)energy quantisation.
C)space quantisation.
D)magnetic orbital quantisation.
E)that particles behave like waves.

Question 22

In terms of a0, where a0 = 0.0529 nm, the radii of the allowed orbits in the Bohr model of the hydrogen atom are given by rn = :

A)
B)
C)
D)na0.
E)n2a0.

Question 23

The Pauli Exclusion Principle states:

A)no two electrons in the same atom can have the same set of quantum numbers.
B)there is an inherent uncertainty in the position and momentum of a particle.
C)when an atom has orbitals of equal energy, the maximum number of electrons will have unpaired spins.
D)when an atom has orbitals of equal energy, the maximum number of electrons will be paired spins.
E)no two atoms can have the same set of quantum numbers.

Question 24

What is the difference in wavelength for spectral lines emitted by hydrogen for transitions from the n = 16 level to the n = 2 level and transitions from the n = 15 level to the n = 2 level? (RH = 1.097 * 107 m-1.)

A)1.0 * 10- m
B)2.0 *10-10 m
C)4.1 * 10- m
D)8.1 *10-10 m
E)1.6 * 10-9 m

Question 25

When using the Pauli Exclusion Principle, we assume the particle's spin angular momentum is of magnitude:

A)
B)
C)
D)( $\pm$ )
E)

Question 26

Which of the following, in which n and m have integer values, is a correct formula for a wavelength emitted by a hydrogen atom?

A)
B)
C)
D)
E)

Question 27

Forbidden transitions and selection rules suggest that:

A)a photon has linear momentum.
B)a photon has energy.
C)a photon has angular momentum.
D)a photon has parity.
E)a photon has mass.

Question 28

A hydrogen atom in the 4f state has a total angular momentum (in terms of ) of magnitude:

A) ( )
B)3
C)6
D)12

Question 29

In an atom that has an electron in a sub-shell for which = 4, with respect to the magnetic field vector the magnetic moment vector of the electron is allowed to be oriented in:

A)any direction.
B) discrete directions
C) - 1 discrete directions.
D) + 1 discrete directions.
E)2 + 1 discrete directions.

Question 30

In an allowed electron transition in a hydrogen atom:

A)( $\Delta$ = 0; = 0, $\pm$ 1. )
B)( $\Delta$ = 0, $\pm$ 1; = $\pm$ 1. )
C)( $\Delta$ = 0, $\pm$ 1; = 0, $\pm$ 1. )
D)( $\Delta$ = $\pm$ 1; = 0, $\pm$ 1. )
E)( $\Delta$ = $\pm$ 1; = $\pm$ 1. )

Question 31

When electrons fill a subshell in which the orbitals have equal energy, the order in which the orbitals are filled is such that:

A)a minimum number of electrons has unpaired spins.
B)a minimum number of electrons has intrinsic angular momentum.
C)a maximum number of electrons has unpaired spins.
D)a maximum number of electrons first fills the next energy level.
E)the maximum number of electrons has the same set of quantum numbers.

Question 32

What angle does the orbital angular momentum make with the z axis of a hydrogen atom in the state n = 3, = 2, = -1?

A)(-66 $\degree$ )
B)66 $\degree$
C)24 $\degree$
D)114 $\degree$
E)73 $\degree$

Question 33

What is the difference in frequency for spectral lines emitted by hydrogen for transitions from the n = 16 level to the n = 2 level and transitions from the n = 15 level to the n = 2 level? (RH = 1.097*107 m-1.)

A)5.65 *10-13 Hz
B)31 Hz
C)1.77 * 1012 Hz
D)2.55 * 1016 Hz
E)1.02 * 1017 Hz

Question 34

The ground state configuration of chlorine (Z = 17) is:

A)1s2 2s2 2p5 3s2 3p6
B)1s2 2s2 2p6 3s2 3p5
C)1s2 2s2 2p6 3s2 3p4 3d1
D)1s2 2s2 2p6 3s2 3p5 4s1
E)1s2 2s2 2p6 3s1 3p7

Question 35

Characteristic x-rays can be produced by bombarding targets with electrons.These x-rays occur when:

A)electrons from higher shells fill the vacant lower shell.
B)electrons fill the vacant valence shell.
C)photons are emitted with energies on the order of 103 eV.
D)photons are emitted with wavelengths on the order of 103 nm.

Question 36

Rubidium (Z = 37) and potassium (Z = 19) are similar to sodium in that they have ____ electron(s) in the outermost shell.

A)five p
B)three p
C)two s
D)one d
E)one s

Question 37

The number of electrons in the n = 4, = 2 subshell in strontium (Z = 38) is ____ the number of electrons in the n =4, =2 subshell in barium (Z = 56).

A)times
B)times
C)equal to
D)times
E)times

Question 38

The magnitude of the spin angular momentum for an electron is equal to:

A)
B)
C)/2
D)( $\pm$ /2 )
E)

Question 39

Quantum physics agrees with the classical physics limit when:

A)the total angular momentum is a small multiple of
B)the total energy is a small multiple of the energy in the lowest quantised state.
C)the difference in energy between adjacent quantised levels becomes vanishingly small.
D)all electron spins are paired so that L = 0.
E)there is a vacancy in an inner level in the atom.

Question 40

Which of the following statements is true?

A)can never be perpendicular to
B)can be aligned parallel to
C)must be perpendicular to
D)can never be aligned parallel to

Question 41

Adam and Eve are contemplating the beauty of the hydrogen atom.Adam claims that the quantum states with a given value of the principal quantum number n can have any value of the orbital quantum number .Eve says that the Snake told her that a state with a given value of could have any value of n.Which one, if either, is correct, and why?

A)Adam, because the man is always right.
B)Adam because n $\le$ -1.
C)Eve, because n $\le$ - 1.
D)Eve, because $\le$ n - 1.
E)Neither, because Adam is wrong and the Snake told a subtle lie.

Question 42

The energy difference between the upper and lower levels in a certain laser is 1.9593 eV.What is the wavelength of the light emitted by the laser?

Question 43

All quantum states forming a sub-shell have the same:

A)principal quantum number n.
B)orbital quantum number
C)orbital magnetic quantum number
D)n, and
E)n and only.

Question 44

Zeke says that the magnitude of the orbital angular momentum in the hydrogen atom has the value L = .Ruth says that the maximum magnitude of the projection of the angular momentum along the direction of a constant magnetic field vector is .Which one, if either, is correct, and why?

A)Ruth, because the maximum value of L is
B)Ruth, because the orbital angular momentum always lines up with a magnetic field so that has its maximum value along the field.
C)Zeke, because the maximum magnitude of is L =
D)Zeke, because the orbital angular momentum always lines up with a magnetic field so that has its maximum value along the field.
E)Neither, because they have interchanged the maximum magnitude of , , and , its maximum projection along a magnetic field direction.

Question 45

A hydrogen atom emits a photon of wavelength 657.7 nm.From what energy state to what lower energy state did the electron jump?

Question 46

All quantum states forming a shell have the same:

A)principal quantum number n.
B)orbital quantum number
C)orbital magnetic quantum number
D)n, and
E)n and only.

Question 47

Suppose a beam of electrons is incident on a collection of hydrogen atoms, all of which are in the lowest energy state (n = 1).What is the minimum energy the electrons can have if they are to excite the hydrogen atoms into the n = 2 state?

Question 48

In the operation of a laser:

A)stimulated emission occurs.
B)there is a population inversion.
C)the excited state will tend to be metastable.
D)the photons emitted will have transitioned to the ground state.
E)For the answers (a), (b), (c), and (d), three are correct and one is incorrect.

Question 49

Aline says that the magnetic moment of an atom originates in the orbital angular momentum of the electron.Bevis says that it comes from the electron spin.Which one, if either, is correct, and why?

A)Aline, because only atoms, not electrons, can have angular momentum.
B)Bevis, because only atoms, not electrons, can have angular momentum.
C)Neither, because electron spin and orbital angular momentum always cancel exactly.
D)Neither, because the magnetic moment of an atom comes only from the spin of the nucleus.
E)Both, because both the orbital angular momentum and the spins of the electrons contribute to the magnetic moment of an atom.