Infinium is a conceptual element with the atomic number ∞ and symbol If. Infinium would contain infinite number of protons, neutrons, and electrons, resulting in infinite mass. Due to tremendous weight, infinium atom would crush to a zero size, called singularity with infinite density. Infinium could be a probable element which makes up black holes exclusively.
Infinium would have elemental properties, and their values are infinite, including melting and boiling points, and thermal and electrical conductivities. Infinium would be stable against radioactivity due to infinite density and gravity preventing decay.
The only logic use of infinium is to serve as finish space of the periodic table game. Whoever lands on infinium first right after ramsium on the extended periodic table (or oganesson on the standard periodic table) without would win the game.