This is Chemrocksium's second version of their periodic table.  Building on Björk's organization using the elements' melting points, another one of Chemrocksium's amazing chemists, Boris Broflovski, found out what each element was reactive to.  Broflovski then put the most reactive elements (the ones that react to water, oxygen, and acid) in the first group, the second most reactive (the ones that react to water and oxygen or acid and oxygen) in the middle, and the least reactive (the ones that reacted only to oxygen or to nothing) on the right.  Broflovski was inspired by the way Earth's periodic table was organized by reactiveness.  To give a higher sense of organization, each column is ordered by increasing melting point moving down the column.       

    Broflovski is also credited with naming each of the groups.  He called the first group the dark group because the elements have a dark color.  He named the second group the oxygen group because all the elements react to oxygen.  Lastly, the final group was named the stoic group because the elements there don't react with anything, with the exception of one that reacts only to oxygen.