Yes, one gallon is 3.785 liter = 3 785 cm3, and at the density of Uranium of 19.1 g/cm3, it gives 72.3 kg which is 160 pounds. Platinum, Iridium, and Osmium are even little bit more dense (Pt 21.5 g/cm3, Ir 22.4 g/cm3, and Os 22.6 g/cm3). So a gallon of Osmium would weight 85.5 kg (190 pounds). Gold and Thungsten, despite their relatively low atomic mass, are pretty dense too (similar to Uranium - over 19 g/cm3). Despite the weight, I'd certainly not refuse if someone handed me over a gallon of pure Gold (also around 160 pounds) or Platinum.
The density of Unbibium is not yet known. Although the atomic number (122) and atomic mass (292) are considerably higher than al all those other known elements (92/238 at U), the density depends also on the crystal structure, which is not yet known (or at least not published yet).
Some more information on Unbibium (including some healthy scepticism):
Developing your Web presence: Unbibium or Unbelievium?