Shell: f-block

 .                                                  ..
 .. ..                               .  .  .  .  .  ..
 .. ..                               .. .. .  .  .. ..
 .  .. .. .. .  .. .. .. .. .. .. .. .. .. .. .. .. ..
 .. .. .  .. .. .. .. .. .. .. .. .. .. .. .. .. .  ..
 .. .. La .. .. .  .. .. .. .. .. .. .. .. .. .. .. ..
 .. .. Ac .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
                                                      
       Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu      
       Th Pa U  Np Pu Am Cm Bk Cf Es Fm Md No Lr      

The f-block consists of elements in the Lanthanides and Actinides 
families. The valence electrons of these elements are in the f-shell. 
This shell holds at most 14 electrons, and has an azimuthal quantum 
number of 3. The "f" stands for "fundamental".

 57 La Lanthanum
 58 Ce Cerium
 59 Pr Praseodymium
 60 Nd Neodymium
 61 Pm Promethium
 62 Sm Samarium
 63 Eu Europium
 64 Gd Gadolinium
 65 Tb Terbium
 66 Dy Dysprosium
 67 Ho Holmium
 68 Er Erbium
 69 Tm Thulium
 70 Yb Ytterbium
 71 Lu Lutetium
 89 Ac Actinium
 90 Th Thorium
 91 Pa Protactinium
 92 U  Uranium
 93 Np Neptunium
 94 Pu Plutonium
 95 Am Americium
 96 Cm Curium
 97 Bk Berkelium
 98 Cf Californium
 99 Es Einsteinium
100 Fm Fermium
101 Md Mendelevium
102 No Nobelium
103 Lr Lawrencium