TEXT Shell: s-block
       
        H                                                  He
        Li Be                               .  .  .  .  .  ..
        Na Mg                               .. .. .  .  .. ..
        K  Ca .. .. .  .. .. .. .. .. .. .. .. .. .. .. .. ..
        Rb Sr .  .. .. .. .. .. .. .. .. .. .. .. .. .. .  ..
        Cs Ba .. .. .. .  .. .. .. .. .. .. .. .. .. .. .. ..
        Fr Ra .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
                                                             
              .. .. .. .. .. .. .. .. .. .. .. .. .. ..      
              .. .. .  .. .. .. .. .. .. .. .. .. .. ..      
       
       The s-block consists of elements in Groups 1 and 2 plus Helium. The 
       valence electrons of these elements are in the s-shell. This 
       spherical shaped shell holds at most 2 electrons, and has an 
       azimuthal quantum number of 0. The "s" stands for "sharp".
       
   DIR   1 H  Hydrogen
   DIR   2 He Helium
   DIR   3 Li Lithium
   DIR   4 Be Beryllium
   DIR  11 Na Sodium
   DIR  12 Mg Magnesium
   DIR  19 K  Potassium
   DIR  20 Ca Calcium
   DIR  37 Rb Rubidium
   DIR  38 Sr Strontium
   DIR  55 Cs Cesium
   DIR  56 Ba Barium
   DIR  87 Fr Francium
   DIR  88 Ra Radium
       
   DIR All Shells