Unit 4 Review

Section I - Problems  (Given h = 6.626 x 10-34 J.s)

1.  The speed of light, c, equals   3.00 x 108     m/s.

2.  What is the frequency of a wave with a wavelength of 3.5 x 108 m?       
c = l . n                         3.00 x 108 m/s = 3.5 x 108 m . n                   n = 0.86   1/s (or Hz)

3.  What is the energy of a photon with a frequency of 5.41 x 10-7  1/s?
E = h . n                                    E = (6.626 x 10-34 J . s) . (5.41 x 10-7  1/s)   E = 3.58 x 10-40 J

4.  Substitute, rearrange, and write an equation that relates E, h, c, and l.
  c   =  l . n                    E = h . n            E = h .  c          
  l          l                                                            l

Section II - Electromagnetic Spectrum

1.  Label both ends of the spectrum with high/low frequency, high/low energy, and long/short wavelength

 Long wavelength           radio waves       microwaves     infrared light        ROYGBIV           ultraviolet light               x-rays        gamma rays      short wavelength
 Low frequency                                                                                                                                                                                      high frequency
 Low energy                                                                                                                                                                                                       high energy

2.  Which has a higher energy, gamma or x-rays?  gamma

3.  Which has a shorter wavelength, radio or ultraviolet? ultraviolet

4.  Which has a lower frequency, yellow or green light? yellow

5.  In the equation E = hn, energy and frequency are  directly  proportional.

6.  In the equation c = ln, wavelength and frequency are  inversely  proportional.

7.  The symbol for wavelength is  l .

8.   Frequency  equals the number of waves that pass a point per second.

9.  Electrons give off energy in the form of a  photon (or quantum)  when returning to the ground state.

10.  Which scientist proposed the idea that electrons travel around the nucleus in fixed paths?          Bohr

11.  When an electron moves from the ground state to the excited state, energy is  absorbed .

12.  Bohr chose the element  hydrogen  to prove his theory.

13.  The dual wave-particle nature of electrons describes how the electrons in atoms can behave as
        waves  and  particles .

Section III - Electrons

1.  What is an electron cloud?  Area around the nucleus where electrons are located

*2.  Who proposed the uncertainty principle?        Heisenberg

*3.  Who is credited with the idea that electrons are placed in the lowest energy level first?  Aufbau

*4.  What rule requires that each of the "p" orbitals (at a particular energy level) receive one electron before any
     of the orbitals can have two electrons?            Hund’s Rule

5.  What is the maximum number of electrons in any orbital?         2

6.  The principal quantum number, n, indicates the  energy level .

7.  The maximum number of electrons in an energy level can be determined by the equation  2 n2    
     That means the maximum number of electrons in the 3rd energy level is  18 .

8.  The number of sublevels in any energy level can be determined by  the number of the energy level .

9.  The number of orbitals in an energy level can be determined by the equation  n2 .
     So, the 3rd energy level has  9  orbitals.  ( 1  is "s" orbital,  3  is/are "p" orbitals, and  5
     is/are "d" orbitals)

10.  List the four sublevels according to increasing energy. s à p à d à f

11.  The "s" sublevel is shaped like a  sphere  and has  1  orbital.

12.  A "p" sublevel is shaped like a  dumbbell  and has  3  orbitals.

13.  The "d" sublevel has  5  orbitals and the "f" sublevel has  7  orbitals.

Section IV - Electron configuration, noble gas configuration, valence electrons, orbital notations

1.  What is the electron configuration for phosphorus?       1s2 2s2 2p6 3s2 3p3

2.  How many total electrons are in a neutral atom of phosphorus?  15

3.  Write the noble gas configuration for phosphorus.  [Ne] 3s2 3p3

4.  What is the highest occupied energy level for phosphorus?  3

5.  What is the atomic number of phosphorus?  15

6.  Draw the orbital notation for phosphorus.  hi  h  h  h
                      3s               3p

7.  How many electrons are in the highest occupied energy level of phosphorus?      5

8.  How many unpaired electrons does phosphorus have?   3

9.  How many inner-shell electrons does phosphorus have?  10

10.  In which orbitals are the inner-shell electrons located?  1s, 2s, 2p

11.  Draw the electron dot diagram for phosphorus.      .
                                                                                    : P .
                                                                                      .

Section V - Quantum numbers (Honors level only)

1.  How many electrons can be described by the quantum numbers n = 3 and l = 1?  6

2.  How many electrons in an atom can have the quantum numbers n = 2 and l = 3?  0

3.  How many "d" orbitals have the value n = 3?  5

4.  How many electrons in an atom have the quantum numbers n = 4 and l = 2?  10

5.  Which of the following sets of quantum numbers does NOT represent a possible set of quantum numbers for a
     hydrogen atom?  (There may be more than one correct answer.)
                   n         l         m        s 
     (A)        4          8        -4       p; 1/2                   maximum value for l = n - 1
     (B)        6          5        -5       p; 1/2
     (C)        3          2         2        1/2
     (D)        6         0          1        1/2       m = -l .. +l

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