Transcript Quantum Mechanics and Atomic Theory

Quantum Mechanics and
Atomic Theory
Chapter 12
E-mail: [email protected]
Web-site: http://clas.sa.ucsb.edu/staff/terri/
Quantum – ch 12
1. A green photon has a frequency (v) of 5.45 x 108 MHz
a. Calculate the photons wavelength (λ) in nm
b. Calculate the energy (in J) of one photon and for one mole of
photons (kJ/mol)
Quantum – ch 12
2. Determine the following:
a. Higher frequency:
b. Higher Energy:
c. Longer wavelength:
IR
or
X-Rays or
yellow or
UV
Microwaves
purple
Quantum – ch 12
3. According to Heisenberg uncertainty principle;
a. the momentum of a particle cannot be measured precisely
b. neither the position nor the momentum can be measured
precisely
c. the position and the momentum of a particle can be
measured precisely, but not at the same time
d. the positon of a particle cannot be measured precisely
Quantum – ch 12
4. From the following list of observations, choose the one that most
clearly supports the conclusion that electrons have wave
properties.
a. the emission spectrum of hydrogen
b. the photoelectric effect
c. the scattering of alpha particles by metal foil
d. diffraction
e. cathode "rays"
Quantum – ch 12
5. Calculate the wavelength of a beryllium atom traveling at 15%
the speed of light.
Quantum – ch 12
6. It takes 208.4 kJ of energy to remove 1 mol of electrons from the
atoms on the surface of rubidium metal. If rubidium metal is
irradiated with 254-nm light, what is the maximum kinetic energy
(kJ/mol) the released electrons can have?
Quantum – ch 12
7. Consider the following transitions. Which will emit light with a
longer wavelength?
a. n = 4  n = 2
or
n=3  n=2
b. n = 3  n = 1
or
n=1  n=3
c. n = 5  n = 3
or
n=3  n=1
Quantum – ch 12
8. Calculate the wavelengths (nm) emitted for the following electronic
transitions in a hydrogen atom.
a. n = 5  n = 3
b. n = 3  n = 1
c. How would your answers vary if the electronic transitions were
for Ne9+?
Quantum – ch 12
9. An excited hydrogen atom with an electron in n = 5 state emits light
having a frequency of 6.9 x 1014 s-1. Determine the principal
quantum level (n) for the final state in this electronic transition.
Quantum – ch 12
10. The figure below represents part of the emission spectrum for a
one-electron ion in the gas phase. All of the lines result from
electronic transitions from excited states to the n = 3 state.
A
B
C
Wavelength
a. What electronic transitions correspond to lines A and B?
b. If the wavelength of line B is 142.5 nm, calculate the
wavelength of line A.
Quantum – ch 12
11. An electron is excited from the ground state to the n = 3 state in a
hydrogen atom. Which of the following statements is/are true?
a. It takes more energy to ionize the electron from n= 3 than from
the ground state.
b. The electron is farther from the nucleus on average in the n = 3
state than in the ground state
c. The wavelength of light emitted if the electron drops from n = 3
to n = 2 is shorter than the wavelength of light emitted if the
electron falls from n = 3 to n = 1.
d. The wavelength of light emitted when the electron returns to the
ground state from n = 3 is the same as the wavelength
absorbed to go from n = 1 to n = 3.
e. The ground state ionization energy of He+ is four times the
ground state ionization of H.
Quantum – ch 12
12. Calculate the ground state ionization energy (in kJ/mol) and the
wavelength (in nm) required for B4+.
Quantum – ch 12
13. How many electrons in any one atom can have the following
quantum numbers?
a. n = 5
b. n = 6, l = 0
c. n = 4, l = 2
d. n = 4, l = 3, ml = -2
e. n = 2, l = 0, ml = 0, ms = -1/2
Quantum – ch 12
Quantum Numbers
1. n ⇒ principal quantum number ⇒ proportional to the size and
energy of the orbital ⇒ range is 1 to ∞
2. l ⇒ angular momentum quantum number ⇒ shape of the subshell ⇒
range is 0 to ∞
3. ml ⇒ magnetic quantum number ⇒ orbital orientation ⇒
range is –l to +l
4. ms ⇒ electron spin quantum number ⇒ +1/2 or -1/2
Quantum – ch 12
Quantum – ch 12
l=0 ⇒ s
l=1 ⇒ p
l=2 ⇒ d
l=3 ⇒ f
Quantum – ch 12
14. Fill in the following table:
Element
Cl
Ni
Cr
Ag
Te2–
Fe2+
Ground State Electron
Configuration
Number of Valence
Electrons
Number of Unpaired
Electrons
Quantum – ch 12
Aufbau principle ⇒ electrons will fill from low to high energy
Hund’s Rule ⇒ When filling degenerate orbitals don’t pair up until each orbital has 1 e–
Quantum – ch 12
Electron
Configuration ⇒
Order of filling is
left to right and top to
bottom on the
periodic table
Quantum – ch 12
15. Determine if each of the following corresponds with an excited
state or ground state electron configuration.
a. [Ar]4s24p5
b. [Kr]6s1
c. [Ne]3s23p4
Quantum – ch 12
16. Which of the following has the largest radius?
a. Al or Si
b. F or Cl
c. K+ or S2d. Ar or K+
Quantum – ch 12
17. Which of the following has the greatest ionization energy?
a. K or Ca
b. P or As
c. Sr or Sr2+
Quantum – ch 12
18. The successive ionization energies for an unknown element are:
I1 = 896 kJ/mol
I2 = 1752 kJ/mol
I3 = 14,807 kJ/mol
I4 = 17,948 kJ/mol
Which family does the unknown element most likely belong?
Quantum – ch 12
19. Which of the following has the most negative electron affinity?
a. Br or Kr
b. C or Si