Heaviest atom with which chemistry has been performed?
According to Adsorption behavior of super-heavy elements (Z 
[greater than or equal to ] 112) on metal and inert surfaces :


  Nowadays the research focusses on the chemical properties of
  the element 114. So far, two gas chromatography experiments to study the interaction strength of
  element 114 with a gold surface have been performed with conflicting results. One experiment [reference 1]
  reported a weak interaction of element 114 with a gold surface, leading to adsorption only at very
  low temperatures of approximately –90°C, while in the second experiment [reference 2] adsorption on gold
  has been observed at the room temperature, indicating a much stronger bond between element 114
  and gold.


See also the earlier: Chemical characterization of element 112 :


  We therefore conclude that the stronger adsorption interaction of element 112 with gold involves formation of a metal bond, which is behaviour typical of group 12 elements