1. List the sublevels or subshells of the first four levels or
  shells.


   1s
   2s 2p
   3s 3p 3d
   4s 4p 4d 4f


2. Write the electronic configurations for the following atoms.


   O     1s22s22p4

   Na    1s22s22p63s1

   Cl    1s22s22p63s23p5

   Ni    1s22s22p63s23p63d84s2

   Fe    1s22s22p63s23p63d64s2

   Hg    1s22s22p63s23p63d104s24p64d104f145s25p65d106s2



3. How many electrons are in the third shell of an iron atom ?


                            14


4. How many valence electrons are in each of the following atoms ?


   Na   1                       Ne   8

   Mg   2                       N    5

   Al   3                       K    1

   C    4                       Si   4

   F    7                       Mn   2

   O    6                       Ni   2