Well by element of the periodic table, it is either osium or iridium, it is hard to tell which one is more dense because of the different isoptes in iridum, but i belive that irdium takes the title with density of 22.65 grams a cubic centimeter and osium 22.61 grams a cubic cm.
Most Dense Material
IRIDIUM 22.65 grams a cubis centimeter
There are probally some ways to condense matter as much of atoms and rocks ect have lots of emoty space and cavities ect, how ever these spaces are not actually empty they contain other enegry, so to change space cahnges energy and changes the substance.
a neutron star, would be a mass or protons converted into neutrons, due to a change in energy,and space.
Hydrogen electron orbital have 5 n quntum, colavent radius of 0.37 Angstroms(Diatomic)
Iridium or osium of the elemetal chart is also the end point of atomic stablity, kind of like hydrogen is the begining, it at least that way on earth. so elements like gold and platiunium mercury and lead ect all the way up to uranium are elements in transmutaion atomically. they my have been stable in earth a long time ago, when earths orbit around the sun was different by some 500,000 miles,million ect....
Why do you want to know the denses material
DWAYNE D.L.RABON