Only very small quantities of the trans-actinide elements have ever been synthesized and observable quantities will probably never be made.  For example, only three atoms of element 118 (ununoctium, Uuo) were synthesizes by fusing krypton-86  with lead-208 in a  449 million electron volt particle accelerator for 11 days at Lawrence Berkeley National Laboratory, California.  The production rate for element 118 was one atom for every 10¹² interactions.

The few atoms that are produced have very short half lives and quickly undergo alpha decay to element 116.  The whole decay chain is below.

¹¹⁸Uuo ¾¾® ¹¹⁶Uuh + ²He (0.12 milliseconds)                

¹¹⁶Uuh ¾¾® ¹¹⁴Uuq + ²He (0.60 milliseconds)

¹¹⁴Uuq ¾¾® ¹¹²Uub + ²He (0.58 milliseconds)

¹¹²Uub ¾¾® ¹¹⁰Uun + ²He (0.89 milliseconds)
                                                                                                
¹¹⁰Uun ¾¾® ¹⁰⁸Hs + ²He (3 milliseconds)

¹⁰⁸Hs ¾¾® ¹⁰⁶Sg + ²He (1200 milliseconds)

So how can the properties and compounds of these elements be investigated?.  Quantum theory can predict properties of heavy element so results of experiments can prove that quantum
effects are well understood. Especially interesting are the consequences of the relativistic effects.  Relativistic effects are caused by high nuclear charge  making the electrons "move" (in the classical interpretation) so fast, that the velocity is near the speed of light. The equivalence of mass and energy (relativity) lets the mass of the electron increase. This causes certain orbitals to change their size and necessarily  the properties. This "relativistic effect" is well known from the further period and can be given as the reason for the colour of gold (which is unique among metals) or the liquidity of mercury. It is expected that the relativistic effects are so strong for heavy trans-actinides that the group classification becomes meaningless.

Despite only having miniscule quantities, compounds of these elements can be studied by using a technique Known as "single atom chemistry".  Single atoms behave differently to macroscopic quantities.  For instance, on macroscopic scale a substance will show some kind of equilibrium, e.g. it could be partly dissolved,  in equilibrium with its vapour, partly dissociated  weak acid etc.

But how does a single atom behave? It cannot be in two states at once.  So the concept of a concentration in an equilibrium changes to a probability for single atoms.  This means that If particular conditions are used in a single atom experiment which lead quickly to an equilibrium, the properties of a single atom are representative for the substance.

Chromatographic methods (HPLC), particularly a method called ARCA (Automated Rapid Chemistry Apparatus) are ideal for this type of experiment. Because of the relative low activation energy of adsorption and desorption in chromatographic systems the equilibrium is reached quickly.  A single atom in a HPLC column changes many times from the mobile phase into the stationary one and vice versa. So the retention time is characteristic for the chemical behaviour of the species.